Bioabsorbable and biocompatible polyurethanes and polyamides for medical devices

ABSTRACT

Absorbable polyurethanes, polyamides and polyester urethanes prepared from at least one compound selected from:  
                 
 
or the diamines and diisocyanates thereof, wherein each X represents a member independently selected from —CH 2 COO— (glycolic acid moiety), —CH(CH 3 )COO— (lactic acid moiety), —CH 2 CH 2 OCH 2 COO— (dioxanone), —CH 2 CH 2 CH 2 CH 2 CH 2 COO— (caprolactone moiety), —(CH 2 ) y COO— where y is one of the numbers 2, 3, 4 or 6-24 inclusive, and —(CH 2 CH 2 O) z′ CH 2 COO— where z′ is an integer between 2 and 24, inclusive; each Y represents a member independently selected from —COCH 2 O— (glycolic ester moiety), —COCH(CH 3 )O— (lactic ester moiety), —COCH 2 OCH 2 CH 2 O— (dioxanone ester), —COCH 2 CH 2 CH 2 CH 2 CH 2 O— (caprolactone ester), —CO(CH 2 ) m O— where m is an integer between 2, 3, 4 or 6-24 inclusive, —COCH 2 O(CH 2 CH 2 O) n — where n is an integer between 2 and 24, inclusive; R′ is hydrogen, benzyl or an alkyl group, the alkyl group being either straight-chained or branched; p is an integer between 1 and 4, inclusive; and Rn represents one or more members selected from H, alkoxy, benzyloxy, aldehyde, halogen, carboxylic acid and —NO 2 , which is attached directly to an aromatic ring or attached through an aliphatic chain. Absorbable polymers prepared from these compounds are useful for drug delivery, tissue engineering, tissue adhesives, adhesion prevention and other implantable medical devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority benefit under 35 U.S.C. § 119(e)of U.S. Provisional Patent Application Ser. No. 60/647,996 filed Jan.28, 2005 and under 35 U.S.C. §120 as a Continuation-In Part of U.S.patent application Ser. No. 11/220,044 filed Sep. 6, 2005. The presentapplication also claims priority benefit under 35 U.S.C. §120 as aContinuation-In-Part of U.S. patent application Ser. No. 11/233,876filed Sep. 23, 2005. The disclosures of all three applications areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the discovery of a new class of amines,isocyanates and bioabsorbable polyurethanes, polyester urethanes andpolyamides prepared there from. The resultant absorbable polymers areuseful for drug delivery, tissue engineering, tissue adhesives, adhesionprevention and other implantable medical devices. In addition, theseabsorbable polymers should have a controllable degradation profile.

BACKGROUND OF THE INVENTION

Biodegradable polymers have become increasingly important for a varietyof biomedical applications including tissue engineering scaffolds.However, relatively few biodegradable, particularly elastomeric,polymers have been developed which are presently in use.

Polymeric medical devices which intentionally degrade and disappear uponcompletion of their function may mitigate the inevitable, usuallynegative physiologic responses (eg. fibrous encapsulation) which maylimit long-term device success. Thus, an array of degradable polymershave been developed and studied for many uses. However, relatively fewof these degradable materials are elastomeric polymers. Rather, themajority of degradable polymers are essentially hard, brittle materialsfor drug delivery uses. With the increasing interest in tissueengineering degradable materials exhibiting a wide variety of physicalproperties are necessary to integrate with the various tissues of thebody.

Segmented polyurethane elastomers have enjoyed wide use as biomaterialsdue to their excellent mechanical properties and great chemicalversatility. The vast majority of research devoted to the development ofbiomedical polyurethanes has focused on long-term applications such asvascular grafts and pacemaker lead insulators.

Despite the progress thus far in the development of polyurethanes,relatively little research has been directed at developing intentionallydegradable polyurethanes for temporary implantation. Several papers werepublished in the early 1980's describing polyurethane/polylactide blendsas degradable materials for skin substitutes, vascular prostheses andnerve regeneration guides. However, in these cases the polyurethaneportion of the blend was non-degradable and served only to providefavorable mechanical properties. Subsequent work by Bruin et al.,“Design and Synthesis of Biodegradable Poly(Ester-Urethane) ElastomerNetworks Composed of Non-Toxic Building Blocks,” Makromol. Chem., RapidCommun., 9, 584-594, (1988) involved the synthesis of crosslinkedpolyurethane networks incorporating lactide or glycolide and.epsilon.-caprolactone joined by a lysine-based diisocyanate. Thesepolymers displayed good elastomeric properties and were found to degradewithin 26 weeks in vitro and 12 weeks in vivo (subcutaneous implantationin guinea pigs).

However, a drawback of this approach is that the highly crosslinkedpolymer may not be processed by standard techniques such as solutioncasting or melt processing as is the case for typical linear, segmentedpolyurethanes. Cohn et al developed a series of elastomericpolyester-polyether-polyurethane block copolymers intended for use assurgical articles (EP295,055). However, these polymers are relativelystiff, low tensile strength materials, which may preclude their use aselastomeric biomaterials.

In recent years there has developed increased interest in replacing oraugmenting sutures with adhesive bonds. The reasons for this increasedinterest include: (1) the potential speed with which repair might beaccomplished; (2) the ability of a bonding substance to effect completeclosure, thus preventing seepage of fluids; and (3) the possibility offorming a bond without excessive deformation of tissue.

Studies in this area, however, have revealed that, in order for surgicaladhesives to be accepted by surgeons, they must possess a number ofproperties. First, they must exhibit high initial tack and an ability tobond rapidly to living tissue. Secondly, the strength of the bond shouldbe sufficiently high to cause tissue failure before bond failure.Thirdly, the adhesive should form a bridge, preferably a permeableflexible bridge. Fourthly, the adhesive bridge and/or its metabolicproducts should not cause local histotoxic or carcinogenic effects.

Isocyanate-based adhesive/sealant compositions are disclosed, forexample, in U.S. Pat. Nos. 6,894,140; 5,173,301; 4,994,542; and4,740,534, the disclosures of which are incorporated herein in theirentirety by this reference.

A number of adhesive systems such as alkyl cyanoacrylates,polyacrylates, maleic anhydride/methyl vinyl ethers, epoxy systems,polyvinyl alcohols, formaldehyde and gluteraldehyde resins andisocyanates have been investigated as possible surgical adhesives. Nonehas gained acceptance because each fails to meet one or more of thecriteria noted above. The principal criticism of these adhesives systemshas been the slow rate of reaction and potential toxicity problems theypose.

BRIEF SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide novelmaterials that are useful for drug delivery, tissue engineering, tissueadhesives, adhesion prevention and other implantable medical devices.

A further object of the present invention is to provide novel polyamideswhich are biodegradable and biocompatible.

A further object of the present invention is to provide novelpolyurethanes which are biodegradable and biocompatible.

A further object of the present invention is to provide novelpolyurethanes, polyamides, polyester urethanes which are biodegradableand biocompatible for tissue engineering.

A further object of the present invention is to provide novel safe,biocompatible and bioabsorbable isocyanate-based adhesives and inparticular metabolically-acceptable surgical adhesives. It would also bedesirable to provide safe, bicompatible surgical adhesives which arebiodegradable. It would also be desirable to provide a method forclosing wounds in living tissue by use of novel,metabolically-acceptable surgical adhesives which are low in toxicity asa consequence of their physical properties.

A further object of the present invention is to provide novelpolyurethanes of the segmented variety which are bioabsorbable.

A further object of the present invention is to provide a chain extenderfor use in the formation of biodegradable polyurethanes.

Briefly stated, the present invention relates to the discovery of a newclass of amines, isocyanates and bioabsorbable polurethanes, polyamidesand polyesterurethanes derived there from. The resultant absorbablepolymers are useful for drug delivery, tissue engineering, tissueadhesives, adhesion prevention and other implantable medical devices. Inaddition, these absorbable polymers should have a controllabledegradation profile.

Accordingly, one aspect of the present invention is to prepare anabsorbable polymer from at least one compound selected from:

Wherein each X represents a member independently selected from:

—CH₂COO— (glycolic acid moiety),

—CH(CH₃)COO— (lactic acid moiety),

—CH₂CH₂OCH₂COO— (dioxanone moiety),

—CH₂CH₂CH₂CH₂CH₂COO— (caprolactone moiety),

—(CH₂)_(y)COO— where y is one of the numbers 2,3,4 or 6-24 inclusive,and

—(CH₂CH₂O)_(z′) CH₂COO— where z′ is an integer between 2 and 24,inclusive;

each Y represents a member independently selected from:

—COCH₂O— (glycolic ester moiety),

—COCH(CH₃)O— (lactic ester moiety),

—COCH₂OCH₂CH₂O— (dioxanone ester moiety),

—COCH₂CH₂CH₂CH₂CH₂O— (caprolactone ester moiety),

—CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24 inclusive, and

—CO CH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24,inclusive;

R′ is hydrogen, benzyl or an alkyl group, the alkyl group being eitherstraight-chained or branched; and p is an integer between 1 and 4,inclusive; and

Rn represents one or more members selected from H, alkoxy, benzyloxy,aldehyde, halogen, carboxylic acid and —NO₂, which is attached directlyto an aromatic ring or attached through an aliphatic chain.

The aromatic compound is selected from amine and/or carboxylic acidcontaining phenols, such as amino phenols, amino salicylic acids andamino benzoic acids.

Accordingly, another aspect of the present invention is to prepareabsorbable polyamides from at least one compound of the formula:

Wherein each X represents a member independently selected from:

—CH₂COO— (glycolic acid moiety);

—CH(CH₃)COO— (lactic acid moiety);

—CH₂CH₂OCH₂COO— (dioxanone moiety);

—CH₂CH₂CH₂CH₂CH₂COO— (caprolactone moiety);

—(CH₂)_(y)COO— where y is one of the numbers 2,3,4 and 6-24 inclusive;and

—(CH₂CH₂O)_(z′)CH₂COO— where z′ is an integer between 2 and 24,inclusive;

each Y represents a member independently selected from:

—COCH₂O— (glycolic ester moiety);

—COCH(CH₃)O— (lactic ester moiety);

—COCH₂OCH₂CH₂O— (dioxanone ester moiety);

—COCH₂CH₂CH₂CH₂CH₂O— (caprolactone ester moiety);

—CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24 inclusive; and

—COCH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24, inclusive;

each R′ is independently a hydrogen, benzyl or an alkyl group, the alkylgroup being either straight-chained or branched, each p is independentlyan integer between 1 and 4, inclusive, Z is O or NH; and

Rn represents one or more members selected from H, alkoxy, benzyloxy,aldehyde, halogen, carboxylic acid and —NO₂, which is attached directlyto an aromatic ring or attached through an aliphatic chain.

The aromatic compound is selected from of amine and/or carboxylic acidcontaining phenols, such as amino phenols, amino salicylic acids andamino benzoic acids.

Another aspect of the present invention is to prepare an absorbablepolyurethane from at least one compound of the formula:

Wherein each X represents a member independently selected from:

—CH₂COO— (glycolic acid moiety);

—CH(CH₃)COO— (lactic acid moiety);

—CH₂CH₂OCH₂COO— (dioxanone moiety);

—CH₂CH₂CH₂CH₂CH₂COO— (caprolactone moiety);

—(CH₂)_(y)COO— where y is one of the numbers 2,3,4 and 6-24 inclusive;and

—(CH₂CH₂O)_(z′)CH₂COO— where z′ is an integer between 2 and 24,inclusive;

each Y represents a member independently selected from:

—COCH₂O— (glycolic ester moiety);

—COCH(CH₃)O— (lactic ester moiety);

—COCH₂OCH₂CH₂O— (dioxanone ester moiety);

—COCH₂CH₂CH₂CH₂CH₂O— (caprolactone ester moiety);

—CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24 inclusive; and

—CO CH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24,inclusive;

each R′ is hydrogen, benzyl or an alkyl group, the alkyl group beingeither straight-chained or branched; and each p is independently aninteger between 1 and 4, inclusive, Z is O or NH; and

Rn represents one or more members selected from H, alkoxy, benzyloxy,aldehyde, halogen, carboxylic acid and —NO₂, which is attached directlyto an aromatic ring or attached through an aliphatic chain.

The aromatic compound is selected from amine and/or carboxylic acidcontaining phenols, such as amino phenols, amino salicylic acids andamino benzoic acids.

A further object of the present invention is to provide novel safe,biocompatible and bioabsorbable isocyanate-based adhesives and inparticular metabolically-acceptable surgical adhesives. It would also bedesirable to provide safe, bicompatible surgical adhesives which arebiodegradable. It would also be desirable to provide a method forclosing wounds in living tissue by use of novel,metabolically-acceptable surgical adhesives which are low in toxicity asa consequence of their physical properties. A further object of thepresent invention is to provide novel polyurethanes which arebiodegradable and biocompatible.

Another object of the present invention is to provide NCO-terminatedhydrophilic polyurethane prepolymer prepared from at least one compoundof the formula and a polyol.

DETAILED DESCRIPTION OF THE INVENTION

The present invention thus provides of a new class of amines,isocyanates and bioabsorbable polurethanes, polyamides andpolyesterurethanes polymerized therefrom. The resultant absorbablepolymers are useful for drug delivery, tissue engineering, tissueadhesives, adhesion prevention and other implantable medical devices. Inaddition these absorbable polymers should have controllable degradationprofile.

The term “bioabsorbable” is defined as those classes of materials thatreadily react or enzymatically degrade upon exposure to bodily tissuefor a relatively short period of time, thus experiencing a significantweight loss in that short time period. Complete bioabsorption shouldtake place within twelve months, although preferably bioabsorption willbe complete within nine months and most preferably within six months. Inthis manner, the polymers of this invention can be fabricated intomedical and surgical devices which are useful for a vast array ofapplications requiring complete absorption within the relatively shorttime periods set forth in the preceding sentence.

The biological properties of the bioabsorbable polymers of thisinvention used to form the device or part thereof, as measured by itsabsorption rate and its breaking strength retention in vivo (BSR), canbe varied to suit the needs of the particular application for which thefabricated medical device or component is intended. This can beconveniently accomplished by varying the ratio of components of thepolymer chosen.

For purposes of defining the scope of this invention, the term “aminophenols” is meant to include 2-aminophenol, 3-aminophenol,4-aminophenol, 2,3-diaminophenol, 2,4-diaminophenol and substitutedequivalents of these compounds, as well as the dimers of thesecompounds.

For purposes of defining the scope of this invention, the term “aminobenzoic acids” is meant to include 2-aminobenzoic acid, 3-aminobenzoicacid, 4-aminobenzoic acid, 2,3-diaminobenzoic acid, 2,4-diaminobenzoicacid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid and substitutedequivalents of these compounds, as well as the dimers of thesecompounds.

For purposes of defining the scope of this invention, the term “aminosalicylic acids” is meant to include 3-aminosalicylic acid,4-aminosalicylic acid 5-aminosalicylic acid, and substituted equivalentsof these compounds, as well as the dimers of these compounds.

For purposes of defining the scope of this invention the term“elastomer” is defined as a material which at room temperature can bestretched repeatedly to at least twice its original length and, uponimmediate release of the stress, will return with force to itsapproximate original length. Preferably, the elastomer exhibits a highpercent elongation and a low modulus, while possessing good tensilestrength and good recovery characteristics. In the preferred embodimentsof this invention, the elastomer from which the medical device orcomponent of the device is formed exhibits a percent elongation greaterthan about 200, preferably greater than about 500. It will also exhibita modulus (Young's Modulus) of less than about 40,000 psi, preferablyless than about 20,000 psi. These properties, which measure the degreeof elasticity of the bioabsorbable elastomer, are achieved whilemaintaining a tensile strength greater than about 500 psi, preferablygreater than about 1,000 psi, and a tear strength of greater than about50 lbs/inch, preferably greater than about 80 lbs/inch

General description of the functionalization of the aromatic compound isselected from amine and/or carboxylic acid containing phenols, such asamino phenols, amino salicylic acids and amino benzoic acids issummarized below. Glycolic acid is used as a functionalization moietyfor illustrative purposes.

Functionalization Moieties

Glycolic acid and lactic acid are also known as alpha hydroxy acids(AHA) present in fruits and other foods. These acids are helpful intreating a variety of skin ailments, such as dry skin, acne, andsunspots. These acids also improve skin texture and lessening finefacial wrinkles. Both glycolic and lactic acids also help loosening andremoving dead skin cells. These acids are present in many healthiestfoods we eat and drink, and they are considered to be safe when usedcorrectly.

Glycolic acid occurs naturally as the chief acidic constituent of sugarcane juice and occurs in beet juice and unripe grapes. Its formula isHOCH₂COOH and is biodegradable. When glycolic acid is heated it readilyloses water by self-esterification to form polyglycolic acid.

Glycolic acid can function as both an acid and an alcohol. This dualfunctionality leads to a variety of chemical reactions and valuablephysical properties. Many surgical devices are made from polyglycolicacid. Studies of cosmetic applications have found that glycolic acid atlow concentrations will diminish the appearance of fine lines on theskin.

The process of attaching a glycolic acid moiety to a phenolic compoundis defined as glycolation and will be referred to as such in describingthis invention:

Lactic acid is a fermentation product of lactose. It is present in sourmilk, koumiss, leban, yogurt, and cottage cheese. Lactic acid isproduced in the muscles during intense activity. Calcium lactate, asoluble lactic acid salt, serves as a source of calcium in the diet.Lactic acid is produced commercially for use in foods andpharmaceuticals. Many surgical and orthopedic devices are made frompolylactic acid. The esters of lactic acid are used as emulsifyingagents in baking foods (stearoyl-2-lactylate, glyceryl lactostearate,glyceryl lactopalmitate).

The process of attaching a lactic acid moiety to a phenolic compound isdefined as lactolation and will be referred to as such in describingthis invention:

Epsilon-caprolactone is a cyclic monomer and is reactive, and thepolymers derived are useful for tailoring specialty polyols andhydroxy-functional polymer resins with enhanced flexibility. The monomerpolymerizes under mild conditions to give low viscosity productssuperior to conventional aliphatic polyesters. Copolymers ofcaprolactone with glycolide and lactide exhibit unique physical andbiological properties as well as different hydrolysis profiles based onthe composition of the monomers.

The process of attaching an open chain ε-caprolactone moiety to aphenolic compound is defined as caprolation and will be referred to assuch in describing this invention:

p-Dioxanone (1,4-dioxan-2-one) is a cyclic monomer and polymers are madevia ring opening polymerization. Polyesters derived from this monomerare used in making absorbable surgical devices with longer absorptionprofile (slower hydrolysis) compared to polyglycolic acid. Theabsorbable surgical devices made from 1,4-dioxan-2-one are proved to bebiologically safe, and biocompatible.

The process of attaching an open chain p-dioxanone moiety to a phenoliccompound is defined as dioxonation and will be referred to as such indescribing this invention:

Many examples of both the phenolic amino acids and the functionalizationmoieties have been shown to be safe and biocompatible. The newfunctionalized phenolics can have controllable hydrolysis profiles,improved bioavailability, improved efficacy and enhanced functionality.The difunctional compounds can readily polymerize into biodegradablepolyesters, polyester amides, polyurethanes, polydiamides, andpolyanhydrides, for example, useful for many applications, includingbiomedical applications, foodstuffs, nutritional supplements, cosmetics,medicaments, coatings and others readily apparent to one skilled in theart.

An object of this invention is to combine these molecules, such asglycolic acid, lactic acid, p-dioxanone, ε-caprolactone, —(CH₂)_(y)COO—,where y is one of the integers 2,3,4 and between 6 and 24 inclusive, and—(CH₂CH₂O)_(z)CH₂COO—, where z is an integer between 2 and 24 inclusive,with phenolic amino acid, to form a new chemical entity. Preferredfunctionalization molecules are glycolic acid, lactic acid, p-dioxanone,and ε-caprolactone. Functionalization enhances the native value of thephenolic amino acid by releasing the phenolic amino acid moiety byhydrolysis or degradation of the compound. The compound degrades undercontrollable conditions in the environment, in the body of an animal,for example a mammalian, including a human.

The glycolic acid moiety, lactic acid moiety, dioxanone moiety,caprolactone moiety, moieties of —(CH₂)_(y)COO— where y is one of thenumbers 2,3,4 and 6-24, and moieties of —(CH₂CH₂O)_(z)CH₂COO— where z isan integer between 2 and 24, including 2 and 24, have differenthydrolysis or degradation rates and times over which they release theactive phenolic amino acid moiety and thus do the functionalizedphenolic acid made from them. The species used for functionalizationsupplies the release time or range dictated by the application. Glycolicacid based compounds hydrolyze faster than p-dioxanone based,, where aslactic acid and caprolactone based compounds take much longer tohydrolyze than glycolic acid and p-dioxanone based compounds. Thisdesired time range may be obtained by using a combination offunctionalized phenolic amino acids, that is, a blend of two or morefunctionalized compounds made from any two or more of the speciesglycolide, lactide, dioxanone and polydioxanone combined with onephenolic amino acid.

One aspect of the present invention combines the phenolic amino acidwith one or more of the selected group of compounds to form afunctionalized phenolic amino acid with uses in medicine, as enhanceddrugs, drug intermediates, cancer preventing agents, nutritionsupplements, nutriceuticals, antioxidants, controlled releasepreparations, cosmetic applications, flavors, coatings, drugintermediates, solvents for drugs, new monomers for polymerization, andwhen polymerized, as polymers for biomedical applications, drugs,nutrition supplements, nutriceuticals, drug delivery, cosmeticapplications, flavors, and coatings.

The array of functionalized phenolic amino acids developed as an aspectof the invention, have a wide range of hydrolysis rates that arecontrollable. The specific moiety or combination of moieties used forfunctionalization yields a compound or mixture with specific hydrolysisranges.

The new functionalized phenolic amino acids have more controllablehydrolysis profiles, improved bioavailability, improved efficacy andenhanced functionality. The difunctional compounds polymerize intobiodegradable polymers, for example, useful for applications, includingbiomedical applications, foodstuffs, cosmetics, medicaments, coatingsand other uses readily apparent to one skilled in the art.

The functionalized phenolics can be prepared according to any recognizedmethod, but the Williamson ether synthesis method is the preferredmethod.

Williamson Synthesis

Preparation of ethers is an important reaction for which a wide varietyof procedures have been developed during the last 100 years. The mostcommonly used method for the preparation of symmetrical andunsymmetrical ethers is the Williamson synthesis, involving a halide andan alkoxide. It is possible to mix the halide and alcohol with solid KOHand DMSO. The reaction involves an SN2 reaction in which an alkoxide ionreplaces a halogen, sulfonyl or a sulfate group. Usually, alkyl halidesare used. The alkoxide can be prepared by the reaction of thecorresponding alcohol with an active metal such as metallic sodium or ametal hydride like NaH acting upon the alcohol. The resulting alkoxidesalt is then reacted with the alkyl halide (sulfonate or sulfate) toproduce the ether in an SN2 reaction.

Recently several new procedures for Williamson synthesis have developedin which the phase transfer catalysis (PTC) appear to very convenientand the reactions can be run under mild conditions with high yields.Most recently, it was reported that ethers could be prepared directlyfrom alcohol and alkyl halides under microwave irradiation in thepresence of a quaternary ammonium salt.

For the synthesis of aromatic ethers, the phenolic compound was reactedwith one member of the group Na metal, NaH, and potassium carbonate toform a phenoxide and then reacted with an alkyl halide to form anaromatic ether as shown below:

The first step of the Williamson ether synthesis is the reaction ofsodium hydride with a phenolic compound. Phenols are more acidic thanalkanols because of resonance stabilization of the conjugated anion.

The resulting phenoxide ion is a powerful nucleophile, and reacts wellwith alkyl halide to form an ether.

The alkyl halide must be primary so that the backside attack is notsterically hindered. When it is not primary, elimination usuallyresults.

The general procedure for functionalizing phenolic compounds: To amixture of phenolic compound, anhydrous potassium carbonate, sodiumiodide and disodium phosphate in anhydrous acetone, while refluxing, thealkyl halide is added and refluxed for a period of from a few hours toseveral days until the reaction is essentially complete. Then theacetone is distilled off, water is added, and crude product is filteredand recrystallized from a solvent or mixture of solvents. Some times theproducts are purified by column chromatography. Solvent systems,reaction conditions, and purification methods are modified based on thephenol compound.

The process of preparing a phenolic ester with glycolic acid is shownbelow:

Benzyloxy acetyl chloride (C₆H₅CH₂OCH₂COCl) was prepared as described inthe following reaction scheme:

Using similar method, C₆H₅CH₂OCH(CH₃)COCl, C₆H₅CH₂O(CH₂)₅COCl, andC₆H₅CH₂OCH₂CH₂OCH₂COCl were synthesized for preparation of phenolicesters of amino acids.

Lactic acid can function as both an acid and an alcohol. This dualfunctionality leads to a variety of chemical reactions and valuablephysical properties. The process of preparing a phenolic ester withlactic acid is shown below:

Epsilon-caprolactone can function as both an acid and an alcohol. Thisdual functionality leads to a variety of chemical reactions and valuablephysical properties. The process of preparing a phenolic ester withepsilon-caprolactone is shown below:

p-Dioxanone can function as both an acid and an alcohol. This dualfunctionality leads to a variety of chemical reactions and valuablephysical properties. The process of preparing a phenolic ester withp-dioxanone is shown below:

The phenolic amino acids and the functionalization moieties of thepresent invention are safe and biocompatible. The new functionalizedphenolic amino acids have controllable hydrolysis profiles, increasedsolubility, improved bioavailability, improved efficacy and enhancedfunctionality. The difunctional compounds readily polymerize intobiodegradable polyesters, polyester amides and polyurethanes, forexample, useful for many applications, including biomedicalapplications, foodstuffs, nutritional supplements, cosmetics,biodegradable chewing gums, flavors, medicaments, coatings and othersreadily apparent to one skilled in the art.

One aspect of this invention is to combine one or more of thesemoieties, such as glycolic acid, lactic acid, p-dioxanone,ε-caprolactone, —CO(CH₂)_(m)O—, where m is one of the integers 2,3,4 andbetween 6 and 24 inclusive, and —COCH₂O(CH₂CH₂O)_(n)— where n is aninteger between 2 and 24, with phenolic compounds, to form a newchemical entity through an esterification process. Preferential examplesof functionalization molecules are glycolic acid, lactic acid,p-dioxanone, and ε-caprolactone. Functionalization enhances the nativevalue of the phenolic compound while improveing its solubility byforming a compound which will controllably release the phenolic moietyinto the environment or into the body of a mammalian, preferably ahuman.

The glycolic ester moiety, lactic ester moiety, dioxanone ester moiety,caprolactone ester moiety, moieties of —CO(CH₂)_(m)O—, where m is one ofthe integers 2,3,4 and between 6 and 24 inclusive, and—COCH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24, havedifferent hydrolysis or degradation rates and times over which theyrelease the active phenolic moiety and thus do the functionalizedphenolic compounds made from them. The species used forfunctionalization supplies the release time or range dictated by theapplication. Glycolic acid based compounds hydrolyze faster thanp-dioxanone based, where as lactic acid and caprolactone based compoundstake much longer to hydrolyze than glycolic acid and p-dioxanone basedcompounds. This desired time range may be obtained by using acombination of functionalized phenolic compounds, that is, a blend oftwo or more functionalized compounds made from any two or more of thespecies glycolide, lactide, dioxanone and polydioxanone combined withone phenolic compound.

The present invention also combines the phenolic amino acid with one ormore of the ester-forming functionalizing group of compounds to form afunctionalized phenolic with uses in medicine, as enhanced drugs, drugintermediates, cancer preventing agents, nutrition supplements,nutriceuticals, antioxidants, controlled release preparations, cosmeticapplications, biodegradable chewing gums, flavors, coatings, drugintermediates, solvents for drugs, new monomers for polymerization, andwhen polymerized, as polymers for biomedical applications, drugs,nutrition supplements, nutriceuticals, drug delivery, cosmeticapplications, flavors, and coatings.

The array of functionalized phenolic compounds developed as an aspect ofthe invention, have a wide range of hydrolysis rates that arecontrollable. The specific moiety or combination of moieties used forfunctionalization yield a compound or mixture with specific,controllable hydrolysis ranges.

The new functionalized phenolic amino acids have more highlycontrollable hydrolysis profiles, increased solubility, improvedbioavailability, improved efficacy and enhanced functionality. They canbe targeted to release the active phenolic component in specific organsor body parts. The difunctional compounds polymerize into biodegradeablepolymers, for example, useful for biomedical applications, foodstuffs,biodegradable chewing gums, implantable medical devices, cosmetics,medicaments, coatings and other uses readily apparent to one skilled inthe art.Synthesis of Phenolic Amides:

Benzyloxyamides are prepared by reacting benzyloxy acetic acid with anamine using dicyclohexylcarbodiimide (DCC) as coupling agent, indichloromethane (DCM) as a solvent. The amine is dissolved in DCM andbenzyloxyacetic acid is added. While maintaining below room temperature,DCC solution in DCM is added dropwise. The reaction generally proceedscleanly for the formation of an amide. The urea formed is not soluble inDCM, and the urea can be filtered off to get the amide. In a secondmethod the amines are reacted with the acid chloride directly using abase, such as K₂CO₃, NaHCO₃ or triethyl amine to neutralize the HCl thatis formed during the reaction. Acetone is a good solvent for thisreaction. Both methods are suitable for preparing benzyloxyamides.Synthesis of Phenolic Esters:

We can use similar conditions as above for preparing benzyloxyesters.Debenzylation

Debenzylations were done using 50% wet Pd/C (5%) with hydrogen pressureup to 4 kg. MeOH or DMF can be as solvents. Dry Pd/C(5%) can be alsoused to avoid ester hydrolysis. DMF, MeOH, or Ethyl acetate can be usedfor this reaction.

The foregoing synthetic methods can be used to prepare the followingmonomers, and an absorbable polymer prepared therefrom:

Wherein each X represents a member independently selected from:

—CH₂COO— (glycolic acid moiety),

—CH(CH₃)COO— (lactic acid moiety),

—CH₂CH₂OCH₂COO— (dioxanone moiety),

—CH₂CH₂CH₂CH₂CH₂COO— (caprolactone moiety),

—(CH₂)_(y)COO— where y is one of the numbers 2,3,4 or 6-24 inclusive,and

—(CH₂CH₂O)_(z′)CH₂COO— where z′ is an integer between 2 and 24,inclusive;

each Y represents a member independently selected from:

—COCH₂O— (glycolic ester moiety),

—COCH(CH₃)O— (lactic ester moiety),

—COCH₂OCH₂CH₂O— (dioxanone ester moiety),

—COCH₂CH₂CH₂CH₂CH₂O— (caprolactone ester moiety),

—CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24 inclusive,

—CO CH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24,inclusive;

R′ is hydrogen, benzyl or an alkyl group, the alkyl group being eitherstraight-chained or branched; p is an integer between 1 and 4,inclusive; and

Rn represents one or more members selected from H, alkoxy, benzyloxy,aldehyde, halogen, carboxylic acid —NO₂, which is attached directly toan aromatic ring or attached through an aliphatic chain.

Many species of both the aminophenolics and the functionalizationmoieties have been shown to be safe and biocompatible. The newfunctionalized aminophenolic compounds have controllable hydrolysisprofiles, increased solubility, improved bioavailability, improvedefficacy and enhanced functionality. The difunctional compounds canreadily polymerize into biodegradable polyamides, polyester-urethanes,polyester amides and polyurethanes, for example, useful for manyapplications, including biomedical applications, such as stents, stentcoatings, drug delivery, and surgical devices and others readilyapparent to one skilled in the art.

One aspect of this invention is to combine one or more of thesemoieties, such as glycolic acid, lactic acid, p-dioxanone,ε-caprolactone, —CO(CH₂)_(m)O—, where m is one of the integers 2,3,4 andbetween 6 and 24 inclusive, and —COCH₂O(CH₂CH₂O)_(n)— where n is aninteger between 2 and 24, with phenolic compounds, to form a newchemical entity through an esterification process. Preferredfunctionalization molecules are glycolic acid, lactic acid, p-dioxanone,and ε-caprolactone. Functionalization enhances the native value of thephenolic compound while improving by its solubility by forming acompound which will controllably release the phenolic moiety into theenvironment or into the body of a mammalian, preferably a human.

The glycolic ester moiety, lactic ester moiety, dioxanone ester moiety,caprolactone ester moiety, moieties of —CO(CH₂)_(m)O—, where m is one ofthe integers 2,3,4 and between 6 and 24 inclusive, and —CO CH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24, have differenthydrolysis or degradation rates and times over which they release theactive phenolic moiety and thus do the functionalized phenolic compoundsmade from them. The species used for functionalization supplies therelease time or range dictated by the application. Glycolic acid basedcompounds hydrolyze faster than p-dioxanone based, where as lactic acidand caprolactone based compounds take much longer to hydrolyze thanglycolic acid and p-dioxanone based compounds. This desired time rangemay be obtained by using a combination of functionalized phenoliccompounds, that is, a blend of two or more functionalized compounds madefrom any two or more of the species glycolide, lactide, dioxanone andpolydioxanone combined with one phenolic compound.

The array of functionalized aminophenolic compounds developed as anaspect of the invention, have a wide range of hydrolysis rates that arecontrollable. The specific moiety or combination of moieties used forfunctionalization yield a compound or mixture with specific,controllable hydrolysis ranges.

These new functionalized aminophenolic compounds have more highlycontrollable hydrolysis profiles, increased solubility, improvedbioavailability, improved efficacy and enhanced functionality. They canbe targeted to release the active aminophenolic component in specificorgans or parts of the body. The difunctional compounds polymerize intobiodegradable polymers, for example, useful for applications, includingbiomedical applications, such as stents, stent coatings, drug delivery,and surgical devices and others readily apparent to one skilled in theart.

Processes for preparing polymers of the invention are provided asfurther embodiments of the invention and are illustrated by thefollowing procedures, as a simplified illustration:

Polyamides can be prepared by self condensation or by reacting with anamino acid(HOOC—R—NH₂)

Polyamides can be prepared by self condensation or by reacting with anamino acid(HOOC—R—NH₂)

The monomer compounds of the invention can be used to polymerizebiocompatible, biodegradable polyurethanes, polyesterurethanes, andpolyamides useful in a variety of applications where delivery of abiologically active compound is desired. Examples of such applicationsinclude, but are not limited to, medical, dental and cosmetic uses.

In another embodiment, copolymers of the absorbable polymers of thisinvention can be prepared by preparing a prepolymer under meltpolycondensation conditions, then adding at least one lactone monomer orlactone prepolymer. The mixture would then be subjected to the desiredconditions of temperature and time to copolymerize the prepolymer withthe lactone monomers.

The polymers of the invention are prepared in accordance with methodscommonly employed in the field of synthetic polymers to produce avariety of useful products with valuable physical and chemicalproperties. The polymers are readily processed into pastes or solventcast to yield films, coatings, microspheres and fibers with differentgeometric shapes for design of various medical implants, and may also beprocessed by compression molding and extrusion.

Polyurethanes, polyester urethanes, and polyamides prepared inaccordance with the present invention have average molecular weights ofabout 1500 to about 100,000 calculated by Gel Permeation Chromatography(GPC) relative to narrow molecular weight polystyrene standards.Preferred Polyurethanes, polyester urethanes, and polyamides haveaverage molecular weights of about 1500 up to about 100,000 calculatedby Gel Permeation Chromatography (GPC) relative to narrow molecularweight polystyrene standards. Preferred Polyurethanes, polyesterurethanes, and polyamides have average molecular weights of about 1500up to about 40,000.

Medical implant applications include the use of polyurethanes, polyesterurethanes, and polyamides to form shaped articles such as vasculargrafts and stents, bone plates, sutures, implantable sensors,implantable drug delivery devices, stents for tissue regeneration, andother articles that decompose into non-toxic components within a knowntime period.

In more detail, the surgical and medical uses of the filaments, films,and molded articles of the present invention include, but are notnecessarily limited to:

Knitted products, woven or non-woven, and molded products including:

a. burn dressings

b. hernia patches

c. medicated dressings

d. fascial substitutes

e. gauze, fabric, sheet, felt or sponge for liver hemostasis

f. gauze bandages

g. arterial graft or substitutes

h. bandages for skin surfaces

i. suture knot clip

j. orthopedic pins, clamps, screws, and plates

k. clips (e.g., for vena cava)

l. staples

m. hooks, buttons, and snaps

n. bone substitutes (e.g., mandible prosthesis)

o. intrauterine devices (e.g., spermicidal devices)

p. draining or testing tubes or capillaries

q. surgical instruments

r. vascular implants or supports

s. vertebral discs

t. extracorporeal tubing for kidney and heart-lung machines

u. artificial skin and others

In another embodiment, the polymer of this invention is used to coat asurface of a surgical article to enhance lubricity of the coatedsurface. The polymer may be applied as a coating using conventionaltechniques. For example, the polymer may be solubilized in dilutesolution of volatile organic solvent, e.g. acetone, methanol, ethylacetate or toluene, and the article immersed in the solution to coat itssurface. Once the surface is coated, the surgical article is removedfrom the solution where it can be dried at an elevated temperature untilsolvent and any residual reactants are removed.

Although it is contemplated that numerous surgical articles (includingbut not limited to endoscopic instruments) can be coated with thepolymer of this invention to improve the surface properties of thearticle, the preferred surgical articles are surgical sutures, stentsand needles. The most preferred surgical article is a suture, mostpreferably attached to a needle. Preferably, the suture is a syntheticabsorbable suture. These sutures are derived, for example, fromhomopolymers and copolymers of lactone monomers such as glycolide,lactide, .epsilon.-caprolactone, 1,4-dioxanone, and trimethylenecarbonate. The preferred suture is a braided multifilament suturecomposed of polyglycolide or poly(glycolide-co-lactide).

The amount of coating polymer to be applied on the surface of a braidedsuture can be readily determined empirically, and will depend on theparticular copolymer and suture chosen. Ideally, the amount of coatingcopolymer applied to the surface of the suture may range from about 0.5to about 30 percent of the weight of the coated suture, more preferablyfrom about 1.0 to about 20 weight percent, most preferably from 1 toabout 5 percent by weight. If the amount of coating on the suture weregreater than about 30 weight percent, then it may increase the risk thatthe coating may flake off when the suture is passed through tissue

Sutures coated with the polymers of this invention are desirable becausethey have a more slippery feel, thus making it easier for the surgeon toslide a knot down the suture to the site of surgical trauma. Inaddition, the suture is more pliable, and therefore is easier for thesurgeon to manipulate during use. These advantages are exhibited incomparison to sutures which do not have their surfaces coated with thepolymer of this invention.

In another embodiment of the present invention when the article is ametal stent, the amount of coating applied to the surface of the articleis an amount which creates a layer with a thickness ranging preferablybetween about 2 to about 20 microns on the stent, more preferably about4 to about 8 microns. If the amount of coating on the stent were suchthat the thickness of the coating layer was greater than about 20microns, or if the thickness was less than about 2 microns, then thedesired performance of the stent as it is passed through tissue may notbe achieved.

In another embodiment of the present invention when the article is asurgical needle, the amount of coating applied to the surface of thearticle is an amount which creates a layer with a thickness rangingpreferably between about 2 to about 20 microns on the needle, morepreferably about 4 to about 8 microns. If the amount of coating on theneedle were such that the thickness of the coating layer was greaterthan about 20 microns, or if the thickness was less than about 2microns, then the desired performance of the needle as it is passedthrough tissue may not be achieved.

Polymers of the present invention can also be incorporated into oralformulations and into products such as skin moisturizers, cleansers,pads, plasters, lotions, creams, gels, ointments, solutions, shampoos,tanning products and lipsticks for topical application.

Another aspect of the present invention provides absorbable polyamidesprepared from at least one compound of the formula:

Wherein each X represents a member independently selected from:

—CH₂COO— (glycolic acid moiety);

—CH(CH₃)COO— (lactic acid moiety);

—CH₂CH₂OCH₂COO— (dioxanone moiety);

—CH₂CH₂CH₂CH₂CH₂COO— (caprolactone moiety);

—(CH₂)_(y)COO— where y is one of the numbers 2,3,4 and 6-24 inclusive;and

—(CH₂CH₂O)_(z′)CH₂COO— where z′ is an integer between 2 and 24,inclusive;

each Y represents a member independently selected from:

—COCH₂O— (glycolic ester moiety);

—COCH(CH₃)O— (lactic ester moiety);

—COCH₂OCH₂CH₂O— (dioxanone ester moiety);

—COCH₂CH₂CH₂CH₂CH₂O— (caprolactone ester moiety);

—CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24 inclusive; and

—COCH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24, inclusive;

R′ is hydrogen, benzyl or an alkyl group, the alkyl group being eitherstraight-chained or branched; p is an integer between 1 and 4,inclusive; and

Rn represents one or more members selected from H, alkoxy, benzyloxy,aldehyde, halogen, carboxylic acid and —NO₂, which is attached directlyto an aromatic ring or attached through an aliphatic chain.

The aromatic compound is selected from amine and/or carboxylic acidcontaining phenols, such as amino phenols, amino salicylic acids andamino benzoic acids.

Processes for preparing polyamides of the invention are provided asfurther embodiments of the invention and are illustrated by thefollowing procedures, as a simplified illustration:

The diamines can be reacted with diisocyantes (OCN-R—NCO) to preparebidegradable poluureas.

Another aspect of the present invention provides an absorbablepolyurethane prepared from at least one compound of the formula:

Wherein each X represents a member independently selected from:

—CH₂COO— (glycolic acid moiety);

—CH(CH₃)COO— (lactic acid moiety);

—CH₂CH₂OCH₂COO— (dioxanone moiety);

—CH₂CH₂CH₂CH₂CH₂COO— (caprolactone moiety);

—(CH₂)_(y)COO— where y is one of the numbers 2,3,4 and 6-24 inclusive;and

—(CH₂CH₂O)_(z′)CH₂COO— where z′ is an integer between 2 and 24,inclusive;

each Y represents a member independently selected from:

—COCH₂O— (glycolic ester moiety);

—COCH(CH₃)O— (lactic ester moiety);

—COCH₂OCH₂ CH₂O— (dioxanone ester moiety);

—COCH₂CH₂CH₂CH₂CH₂O—(caprolactone ester moiety);

—CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24 inclusive; and

—CO CH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24,inclusive;

each R′ is hydrogen, benzyl or an alkyl group, the alkyl group beingeither straight-chained or branched; each p is independently an integerbetween 1 and 4, inclusive, Z is O or NH; and

Rn represents one or more members selected from H, alkoxy, benzyloxy,aldehyde, halogen, carboxylic acid and —NO₂, which is attached directlyto an aromatic ring or attached through an aliphatic chain.

The aromatic compound is selected from amine and/or carboxylic acidcontaining phenols, such as amino phenols, amino salicylic acids andamino benzoic acids.

A further object of the present invention is to provide novel safe,biocompatible and bioabsorbable diisocyanate-based adhesives and inparticular metabolically-acceptable surgical adhesives. It is also anobject to provide safe, bicompatible surgical adhesives which arebiodegradable. It would also be desirable to provide a method forclosing wounds in living tissue by use of novel,metabolically-acceptable surgical adhesives that are low in toxicity asa consequence of their physical properties.

It is a further object of the present invention to provide novelpolyurethanes which are biodegradable and biocompatible.

It is a further object of the present invention to provide novelpolyurethanes of the segmented variety which are bioabsorbable.

It is a further object of the present invention to provide a chainextender for use in the formation of biodegradable polyurethanes.

Processes for preparing polyurethanes of the invention are provided asfurther embodiments of the invention and are illustrated by thefollowing procedures, as a simplified illustration:

These isocyanates can be reacted with diamines (H₂N—R—NH₂) to preparebiodegradable polyureas

Chain Extenders: the nature of the chain extender group “R” in a polymerof the invention is not very critical provided the polymer of theinvention possesses acceptable mechanical properties and releasekinetics for the selected therapeutic application. The chain extendergroup R is typically a divalent organic radical having a molecularweight of from about 60 to about 5000. More preferably, R has amolecular weight of from about 100 to about 1000.

The chain extender group may be biologically inactive, or may itselfpossess biological activity. The chain extender group can also be apolyethylene oxide. The chain extender group can also be polyestersderived from at least one lactone monomer, such as glycolide, lactide,p-dioxanone, trimethylenecarbonate, and caprolactone. The chain extendergroup can also comprise other functional groups (including hydroxygroups, amine groups, carboxylic acids, as well as others) that can beused to modify the properties of the polymer (e.g. for branching, forcross linking).

The mechanical properties, such as ultimate tensile strength, ofpolyurethanes made according to the present invention may in some casesbe influenced primarily by the polyol as opposed to the hard segment asin typical segmented polyurethanes.

Suitable diols or polydiols for use in the present invention are diol ordiol repeating units with up to 8 carbon atoms. Examples of suitablediols include diols selected from 1,2-ethanediol (ethylene glycol),1,2-propanediol (propylene glycol), 1,3-propanediol, 1,4-butanediol,1,5-pentanediol, 1,3-cyclopentanediol, 1,6-hexanediol,1,4-cyclohexanediol, 1,8-octanediol and combinations thereof. Examplesof preferred polydiols include polydiols selected from polyethyleneglycol and polypropylene glycol with molecular weights of 500-10000.

Preferably, the polyurethane is of the type known as segmentedpolyurethane, which is characterized by a formation of repeating softand hard blocks formed from such things as a polyol, a diisocyanate anda chain extender and can occur in a linear, branched or networked form.The term chain extender is intended to refer to a multi-functionalmolecule which may be reacted with the previously synthesized prepolymerto generate a high molecular weight polyurethane for example. However,the formation of polyurethane may also be carried out using suchprocesses as a single step process involving reaction of the chainextender with the diisocyanate and the polyol which do not involve theformation of a prepolymer.

Preferably, the polyol is selected according to toxicity when brokendown or otherwise liberated. Two examples of appropriate polyols arepolyethylene oxide and polycaprolactone diol. Others, which may besuitable in some cases. The constituents making up the polyurethane maybe selected so as to be biodegradeable to substantially nontoxicconstituents. The term ‘substantially non-toxic’ is intended to refer tomaterials which when present in the body are physically tolerable and,more specifically, do not cause appreciable cell death (cytotoxicity) ordetrimental alteration of normal cell function (such as mutagenicresponse). This would of course depend on the area of application. Forexample, detailed in vivo tests may be appropriate to determine theeffect of the material on the neighboring cells.

Depending on the formation route selected, these cleavable sites may beregular along the length of the chain extender, thereby giving thesegmented polyurethane a biodegradeability which is, by some measure,predictable. Biodegradability is influenced by a number of factors,including crystallinity.

The hydrophilicity of the polymer may also influence the degradability,that is, the extent to which water is accessible to the polymer matrix.In those cases where the chain extender has enzyme recognizable sidegroups, the access of the water to the surface of the matrix shouldincrease the rate at which the enzyme can catalyze the reaction betweenwater and the hydrolyzable cleavage sites.

The number of cleavage sites also influence biodegradability. The higherthe number of sites generally, the greater the rate of degradation.Preferably, the cleavable site is an ester site and, more preferably,the cleavable ester site is adjacent one or more amino acids. Thisprovides segmented polyurethanes with cleavable sites in its chainextender that may be arranged to be recognizable by enzymes.

In one embodiment, the diisocyanate is reacted with the soft segmentpolyol, in suitable conditions to form a prepolymer; and the prepolymeris then reacted with the chain extender, again in suitable conditions,to form the polyurethane.

Alternatively, multi-functional components could be employed to producea cross-linked network, and hence non-linear, segmented polyurethane.This for example, could be achieved by the use of a branched complexbearing more than two hydroxyl groups, such as for example a triol. Inanother case, certain amino acids may also contribute to the formationof a networked polymer. Lysine for example, having an amine group on itsside chain, may be reacted with such sites as a isocyanate group on thediisocyanate. Additionally, several lysines may be present in the aminoacid group thereby providing potential bonding sites between eachcorresponding amine and another site such as an isocyanate group. Thus,such multi-functional components allow for the formation of nonlinearsegmented polyurethane.

Thus, in one embodiment, substantially non-toxic degradable polyurethanecan be formed from amino acids and substantially non-toxic diols, insuch a manner to be useful as biomaterials for a variety of applicationssuch as artificial skin, wound dressings, tissue engineering scaffoldsand the like. The polyurethane materials may be formed by melt andsolvent processing techniques such as dissolving the polymer into asolvent, pouring the mixture onto a flat sheet or into a mold andevaporating the solvent, with the polymer remaining therein. Other meltprocessing techniques may be available by melting a blank ofpolyurethane and manipulating it into a shape as desired, includingtubes and fibers. A porous polyurethane may be formed in a number ofways, including the addition of a gas (typically carbon dioxide) intothe polymerization reaction, trapping the gas into the polymerstructure. Alternatively, salt crystals can be added to the solventpolymer mixture during casting wherein the salt is not dissolved. Themixture may be deposited into a dish causing the solvent to evaporate,with the salt material being removed by washing with water.

The polyurethane material formed herein may be used in a number ofdifferent forms and in a range of applications, both in the biomedicalfield and others. The material may be fabricated by casting or othermolding techniques to form a substrate, which can be used along orcombined with other substrates to form homogenous multi-layeredmaterials. Such multilayered homogeneous polyurethane materials may beformed with layers having different degrees of degradability. Suchsubstrates may range in thickness from about 1 micron to about 5millimeters for applications suitable for skin repair and the like andperhaps more particularly from about 10 microns to 3.5 millimeters, andstill perhaps more particularly from about 50 microns to about 2millimeters. The thinner the substrate, the more care is needed inhandling.

In the case of bone regeneration and the like, the polyurethane materialmay range in thickness from about 1 cm to about 5 cm or higher,depending on the specific application, including the dimensions of thebone being regenerated. Alternatively, the layered polyurethane materialmay be combined with other naturally occurring materials such as plantmaterials or biological materials such as prepared animal tissue (in acellularized form or otherwise), cell layers and the like. The layeredpolyurethane material may also be combined with other non-naturallyoccurring materials such as other polymer layers, fabric layers and thelike.

Such uni- and multi-layered materials utilizing the polyurethanematerials described herein may have a number of useful applications inthe biomedical field, such as to function as a tissue scaffoldingmaterial, a wound dressing or the like.

The polyurethane material may also be formed as an impermeable film orbulk material or in a porous form and may be a suitable site toestablish a cell layer, for example to be used in the seeding ofregenerative tissue layers, in such cases as in the healing of skinwounds and the like.

The polyurethane material is believed to be especially useful for use asa tissue engineering scaffold which is a structure for the growth orregeneration of tissue. The polyurethane lends itself to such uses sincethe enzyme catalyzed degradation may in some cases work concurrentlywith the migration or growth of cells into the material, while desirablydegrading in the process into its substantially non-toxic constituents.For example, testing of polyurethane made according to the presentinvention, has indicated significant surface modification in thepresence of an enzyme in solution, and which is believed to be caused byenzyme catalyzed cleavage, gradually opening the matrix to cellmigration as a result. It is also possible, in some cases, that cellsmigrating into or located adjacent the matrix, may themselves exudeproteolytic enzymes which will likewise mediate further hydrolyticcleavage.

Such tissue engineering scaffolds may have applications in theregeneration of skin and other organs, bone, cartilage, ligaments,tendons, bladder and other tissue. The polyurethane material may also beuseful in the production of sutures, which require good mechanicalstrength, and drug release matrices, in view of their need for non-toxicdegradability. The polyurethane material may also be useful for othernon-biomedical applications, where degradability into substantiallynon-toxic constituents is an asset. The polyurethane material lendsitself to sterilization by such techniques as gamma radiation andethylene oxide treatments.

In another embodiment of the present invention, the inventive polymerscan be used as a pharmaceutical carrier in a drug delivery matrix. Thematrix is formed by mixing the polymer with a therapeutic agent. A vastvariety of different therapeutic agents can be used in conjunction withthe polymers of the invention. In general, therapeutic agentsadministered via the pharmaceutical compositions of the inventioninclude, without limitation: antiinfectives such as antibiotics andantiviral agents; analgesics and analgesic combinations; anorexics;antihelmintics; antiarthritics; anti-asthmatic agents; anticonvulsants;antidepressants; antidiuretic agents; antidiarrheals; antihistamines;antiinflammatory agents; antimigraine preparations; antinauseants;antineo-plastics; antiparkinsonism drugs; antipruritics; antipsychotics;antipyretics, antispasmodics; anticholinergics; sympathomimetics;xanthine derivatives; cardiovascular preparations including calciumchannel blockers and beta-blockers such as pindolol and antiarrhythmics;antihypertensives; diuretics; vasodilators including general coronary,peripheral and cerebral; central nervous system stimulants; cough andcold preparations, including decongestants; hormones such as estradioland other steroids, including corticosteroids; hypnotics;immunosuppressives; muscle relaxants; para-sympatyholytics;psychostimulants; sedatives; and tranquilizers; and naturally derived orgenetically engineered proteins, polysaccharides, glycoproteins orlipoproteins.

The drug delivery matrix may be administered in any suitable dosage formsuch as oral, parenteral, subcutaneously as an implant, vaginally or asa suppository. Matrix formulations containing polymers of the inventionmay be formulated by mixing one or more therapeutic agents with thepolymer. The therapeutic agent may be present as a liquid, a finelydivided solid, or any other appropriate physical form. Typically, thematrix will include one or more additives, e.g., nontoxic auxiliarysubstances such as diluents, carriers, excipients, stabilizers or thelike. However, the presence of such additives is entirely optional.Other suitable additives may be formulated with the polymers of thisinvention and pharmaceutically active agent or compound, however, ifwater is to be used it should be added immediately beforeadministration.

The amount of therapeutic agent will be dependent upon the particulardrug employed and medical condition being treated. Typically, the amountof drug represents about 0.001% to about 70%, more typically about 0.01%to about 50%, and most typically about 0.1% to about 20% by weight ofthe matrix.

The quantity and type of polymer incorporated into a parenteral dosageform will vary depending on release profile desired and the amount ofdrug employed. The product may contain blends of polymers of thisinvention to provide the desired release profile or consistency to agiven formulation.

The polymers of this invention, upon contact with body fluids includingblood or the like, undergoes gradual degradation (mainly throughhydrolysis) with concomitant release of the dispersed drug for asustained or extended period (as compared to the release from anisotonic saline solution). This can result in prolonged delivery (over,one to 2,000 hours, preferably two to 800 hours) of effective amounts(say, 0.0001 mg/kg/hour to 10 mg/kg/hour) of the drug. This dosage formcan be administered as is necessary depending on the subject beingtreated, the severity of the affliction, the judgment of the prescribingphysician, and the like.

Individual formulations of drugs and polymers of this invention may betested in appropriate in vitro and in vivo models to achieve the desireddrug release profiles. For example, a drug could be formulated with apolymer of this invention and orally administered to an animal. The drugrelease profile is monitored by appropriate means such as, by takingblood samples at specific times and assaying the samples for drugconcentration. Following this or similar procedures, those skilled inthe art are able to formulate a variety of formulations.

Embodiments of the present invention will be described with reference tothe following Examples, which are presented for illustrative purposesonly and are not intended to limit the scope of the invention. Meltingpoints were measured for all products by using a Polmon (MP 96) meltingpoint apparatus. For all the products, NMR was run using a Varian 200MHz and tetramethylsilane as an internal standard.

EXAMPLE 1 (4-Acetylamino-phenoxy)-acetic acid ethyl ester (1)

Ethyl bromoacetate (452 g, 2.7 mol.) was added to a mixture ofparacetamol (300 g, 1.984 mol) and anhydrous K₂CO₃ (1.80 kg, 7.814 mmol)in anhydrous acetone (3 L) and refluxed for 16 hours. Acetone wasdistilled and water (5 L) was added. Crude 1 was filtered, dried andrecrystallised from a mixture of toluene:hexane (1:5) to give pure 1(377 grams, 80%) as a white shining powder. The melting point was foundto be 104.2-106.2° C.

EXAMPLE 2 (4-Amino-phenoxy)acetic acid HCl (2)

(4-Acetylamino-phenoxy)-acetic acid ethyl ester 1 (375 grams, 1.582mmol), in concentrated Hydrochloric acid (9.36 liters) was refluxed for12 Hours. Excess concentrated Hydrochloric acid was distilled off invacuum and filtered hot. The mixture was cooled to 10° C., filtered anddried to give pure 2(250 g, 77.6%) as a wheat colored powder.

M.p: 224-226° C.; ¹HNMR (D₂O) δ 4.68 (s, 2H, OCH2), 3.65 (s, 3H, ester),7.0 (d, 2H, Ar), 7.30 (d, 2H, Ar)

Example 3 (4-Amino-phenoxy)-acetic acid methyl ester (3)

Method A

Through a mixture of (4-Amino-phenoxy) acetic acid HCl 2 (250 g, 1.228mol) in methanol (5 liters) was passed dry HCl gas at 10° C. for onehour and refluxed for ten hours. Methanol (3.5 liters) was distilled offand ice water (1 liter) was added and the pH was adjusted to 7.5 withK₂CO₃. Crude 3 was filtered, dried and recrystallized from a mixture ofchloroform:hexane (1:5) to give pure 3 (130 g, 58.5%) as a light brownpowder

Method B

Methyl (4-nitrophenoxy) acetate 7 (30 grams, 142.18 mol) was dissolvedin methanol (150 ml) in a pressure vessel. Raney nickel (20 g) was addedand the mixture stirred under atmosphere of hydrogen (4 kg) for 8 hours.Catalyst was removed by filtration and methanol distilled off undervacuum. Crude 3 was purified by column chromatography on silica gelusing chloroform as eluant to get pure 3 (22 grams, 85.5%) as a lightbrown powder.

M.p: 65-66.8° C.; ¹HNMR (CDCl₃) δ 3.04 (bs, 2H, NH2), 3.78 (s, 3H,ester), 4.54 (s, 2H, CH2), 6.58 (d, 2H, Ar), 6.72 (d, 2H, Ar)

EXAMPLE 4 (4-Isocyanato-phenoxy)-acetic acid methyl ester (4)

To a mixture of (4-aminophenoxy)-acetic acid methyl ester 3 (15 g, 82.87mmol) and triethylamine (16.77 g, 165.73 mmol) in toluene (225 ml) undernitrogen atmosphere at 0° C. was added triphosgene (9 g, 30.33 mmol) inone lot. The reaction was exo-thermic and the temperature rose to 25° C.Later the reaction mixture was heated to 75° C. over a period of onehour and maintained at this temperature for 26 hours. The reactionmixture was cooled to room temperature, the solids were filtered off,and toluene was distilled off under vacuum to get crude 4, which wasvacuum distilled to get pure 4 (10 grams, 58.3%) as a white powder withan m.p between 50-53° C.

EXAMPLE-5 [4-(2-Hydroxy-ethoxycarbonylamino)-phenoxy]-acetic acid methylester (5)

(4-Isocyanatophenoxy)-acetic acid methyl ester 4 (15 g, 72.46 mmol) wasadded to ethylene glycol (30 ml) at room temperature. The reaction wasexothermic and the temperature rose to 42° C. Later the reaction mixturewas stirred at room temperature for 16 hours. Water (100 ml) was addedand crude 5 was filtered, dried and purified by column chromatography onsilica gel using chloroform as eluant to get pure 5 (16.17 g, 82.9%) asan off-white powder with an m.p between 85.5-87.5° C.

EXAMPLE-6{4-[2-(4-Methoxycarbonylmethoxy-phenylcarbamoyloxy)-ethoxycarbonylamino]-phenoxy}-aceticacid methyl ester (6)

To [4-(2-Hydroxyethoxycarbonylamino)-phenoxy]-acetic acid methyl ester 5(1 g, 3.72 mmol) in toluene (10 ml) was added(4-Isocyanatophenoxy)-acetic acid methyl ester 4 (0.8 gram, 3.8 mmol) atroom temperature and heated to 50° C. for 20 hours. Toluene wasdistilled off and water (10 ml) was added. Crude 6 was extracted intochloroform, dried over sodium sulphate, distilled and purified by columnchromatography on silica gel using chloroform as eluant to g pure 6 (1gram, 56.5%) as a white fluffy powder.

EXAMPLE 7 Methyl (4—Nitro phenoxy) acetate (7)

To a mixture of 4-nitrophenol (100 g, 719 mmol) and anhydrous K₂CO₃ (400gm, 2.894 mol) in anhydrous acetone (950 ml) was added methylchloroacetate (114 g, 1.050 moles) and refluxed for 12 hours. Acetonewas distilled off and water (1500 ml) was added. Crude 7 was filtered,dried and recrystallised from a mixture of ethyl acetate:hexane (1:5) togive pure 7 (110 g, 72.5%) as a white fluffy powder with an m.p between97-98.4° C.

EXAMPLE 8 2-(4-Acetylamino-phenoxy)-propionic acid methyl ester (8)

To a mixture of paracetamol (150 g, 992 mmol), anhydrous K₂CO₃ (540 kg,3.91 mol) and sodium iodide (18 gm, 120 mmol) in anhydrous acetone (3 L)was added methyl 2-chloropropionate (180 g, 1.469 mmol) and refluxed for80 hours. The acetone was distilled off and water (3 L) was added. Crude8 was extracted into chloroform, dried over Na₂SO₄, distilled and hexane(750 ml) was added. The solids were then filtered and recrystallised inmethanol to give pure 8 (95 g, 40.4%) as a white powder with an m.pbetween 96.5-98.2° C.

HPLC: 99%; ¹HNMR (CDCl₃) δ 1.60 (d, 3H, CH₃), 2.08 (s, 3H, O═C—CH₃),3.76 (s, 3H, ester), 4.66 (q, 1H, CH), 6.72 (d, 2H, Ar), 7.32 (d, 2H,Ar), 8.04 (bs, 1H, NH)

EXAMPLE 9 2-(4-Amino-phenoxy)-propionic acid (9)

2-(4-Acetylaminophenoxy)-propionic acid methyl ester 8 (320 g, 1.35 mol)in conc. HCl (8 L) was refluxed for 48 hours. Excess conc. HCl wasdistilled off in vacuum and filtered hot. The mixture was cooled to 10°C., filtered and dried to give pure 9 (240 g, 81.7%) as a brown powderwith an m.p between 175-180° C.

EXAMPLE 10 2-(4-Amino-phenoxy)-propionic acid methyl ester (10)

Method-A

Through a mixture of 2-(4-aminophenoxy)-propionic acid 9 (240 g, 1.103mmol) in methanol (4.8 liters) was passed dry HCl gas at 10° C. for 1hour followed by reflux for 48 hours. Methanol (2.5 liter) was distilledoff, ice water (1 liter) was added and the pH was adjusted to 7.5 withK₂CO₃. Crude 10 was extracted into chloroform, washed with 5% NaHCO₃solution, water, dried over Na₂SO₄ and distilled to give 10 (80 g,37.2%) as a brown syrup.

Method-B

2-(4—Nitrophenoxy)-propionic acid methyl ester 14 (20 g, 88.88 mmol) wasdissolved in dimethyl formamide (100 ml) in a pressure vessel, Raneynickel (20 grams) was added and the mixture stirred under an atmosphereof hydrogen (4 kg) for 6 hours. The catalyst was removed by filtrationand the dimethyl formamide distilled off under vacuum. Crude 10 waspurified by column chromatography on silica gel using chloroform aseluant to get pure 10 (15 g, 86.55%) as a brown syrup.

¹HNMR (CDCl₃) δ 1.56 (d, 3H, CH₃), 2.9 (bs, 2H, NH₂), 3.72 (s, 3H,ester), 4.58 (q, 1H, CH), 6.53 (d, 2H, Ar), 6.68 (d, 2H, Ar)

EXAMPLE-11 2-(4-Isocyanato-phenoxy)-propionic acid methyl ester (11)

To a mixture of 2-(4-aminophenoxy)-propionic acid methyl ester 10 (15 g,76.9 mmol) and triethylamine (15.6 g, 154.16 mmol) in toluene (210 ml)under nitrogen atmosphere was added triphosgene (8.4 g, 28.3 mmol) inone lot. Later the reaction mixture was heated to 75° C. over a periodof one hour and maintained at this temperature for 26 hours. Thereaction mixture was cooled to room temperature, the solids filteredoff, and the toluene was distilled off under vacuum to get crude 11,which was vacuum distilled to get pure II (9 grams, 52.9%) as a lightyellow syrup.

EXAMPLE 12 2-[4-(2-Hydroxy-ethoxycarbonylamino)-phenoxy]-propionic acidmethyl ester (12)

2-(4-Isocyanatophenoxy)-propionic acid methyl ester 11 (20 g, 90.49mmol) was added to ethylene glycol (40 ml) at room temperature. Thereaction was exothermic and the temperature rose to 58° C. This wasfollowed by stirring at room temperature for 16 hours. Water (150 ml)was added and crude 12 was extracted in to chloroform, washed with water(2×50 ml), dried over sodium sulphate and distilled. Crude 12 waspurified by column chromatography on silica gel using chloroform aseluant to get pure 12 (13 g, 50.76%) as a syrup which crystallized in 48hours as a white powder with an m.p between 90.5-92.8° C.

EXAMPLE-132-(4-{2-[4-(1-Methoxycarbonyl-ethoxy)-phenylcarbamoyloxy]-ethoxycarbonylamino}-phenoxy)-propionicacid methyl ester (13)

To 2-[4-(2-Hydroxyethoxycarbonylamino)-phenoxy]-propionic acid methylester 12 (5 g, 17.66 mmol) in toluene (50 ml) was added2-(4-Isocyanatophenoxy)-propionic acid methyl ester 13 (3.9 g, 17.64mmol) at room temperature and heated to 60° C. for 30 hours. Toluene wasdistilled off and water (50 ml) was added. The solid was filtered anddried to give crude 13, which was purified by column chromatography onsilica gel using chloroform as eluant to get pure 13 (5.5 g, 61.8%) as awhite powder with an m.p between 98-100° C.

EXAMPLE 14 2-(4-Nitrophenoxy)-propionic acid methyl ester (14)

To a mixture of 4-nitrophenol (200 grm, 1.439 mol), anhydrous K₂CO₃ (800grm, 5.789 mol) and sodium iodide (10 g, 66.7 mmol) in anhydrous acetone(2.75 L) was added methyl 2-chloropropionate (264 g, 2.154 mol) andrefluxed for 20 hours. Acetone was distilled off and water (3 L) wasadded. Crude 14 was filtered, dried and recrystallised from a mixture ofethyl acetate:hexane (1:5) to give pure 14 (100 g, 31%) as a whitefluffy powder with a m.p between 83-84° C.

EXAMPLE 15 6-(4-Acetylaminophenoxy)-hexanoic acid methyl ester (15)

To a mixture of paracetamol (250 gm, 1.654 mmol), anhydrous K₂CO₃ (800gm, 5.789 mmol) and sodium iodide (17 g, 113 mmol) in anhydrous acetone(5 L) was added methyl 6-bromohexanoate (470 g, 2.25 mmol) and refluxedfor 60 hours. Acetone was distilled off and water (3 L) was added. Crude15 was filtered, dried and recrystallised from a mixture ofchloroform:hexane (1:5) to give pure 15 (195 g, 66%) as a white powderwith an m.p between 96.4-98.8° C.

HPLC: 99%; ¹HNMR (CDCl₃) δ 1.54 (m, 2H, CH₂), 1.80 (m, 4H, CH₂), 2.14(s, 3H, O═C—CH₂), 2.38 (t, 2H, CH₂), 3.68 (s, 3H, ester), 3.92 (t, 2H,OCH₂), 6.68 (d, 2H, Ar), 7.05 (bs, 1H, NH), 7.38 (d, 2H, Ar).

EXAMPLE 16 6-(4-Amino-phenoxy)hexanoic acid hydrochloride (16)

6-(4-acetylaminophenoxy)-hexanoic acid methyl ester 15 (290 g, 1.04mol), in conc. HCl (7.12 L) was refluxed for 48 hours. Excess conc. HClwas distilled off in vacuum and filtered hot. The mixture was cooled to10° C., filtered and dried to give pure 16 (150 g, 55.6%) as a brownpowder with an m.p between 155-160° C.

EXAMPLE 17 6-(4-Aminophenoxy)-hexanoic acid methyl ester (17)

Method-A

Through a mixture of 6-(4-aminophenoxy)-hexanoic acid hydrochloride 16(150 g, 578 mmol) in methanol (3 L) was passed dry HCl gas at 10° C. for1 hour and refluxed for 48 hours. Methanol (1.5 L) was distilled off,ice water (1 L) was added and the pH adjusted to 7.5 with K₂CO₃. Crude17 was extracted into chloroform, washed with 5% NaHCO₃ solution, thenwater, and then dried over Na₂SO₄ and distilled to give 17 (60 g, 43.8%)as a thick brown syrup.

Method-B

6-(4—Nitrophenoxy)-hexanoic acid methyl ester 21 (40 g, 149.81 mmol) wasdissolved in dimethyl formamide (200 ml) in a pressure vessel. Raneynickel (20 g) was added and the mixture stirred under an atmosphere ofhydrogen (4 kg) for 16 hours. Catalyst was removed by filtration anddimethyl formamide distilled off under vacuum. Crude 17 was purified bycolumn chromatography on silica gel using chloroform as eluant to getpure 17 (28 grams, 78.8%) as a thick brown syrup.

¹HNMR (CDCl₃) δ 1.5 (m, 2H, CH₂), 1.72 (m, 4H, CH₂), 2.34 (t, 2H, CH₂),3.66 (s, 3H, ester), 3.85 (t, 2H, OCH₂), 6.56 (d, 2H, Ar), 6.68 (d, 2H,Ar).

EXAMPLE-18 6-(4-Isocyanatophenoxy)-hexanoic acid methyl ester (18)

To 6-(4-aminophenoxy)-hexanoic acid methyl ester 17 (26 g, 109.7 mmol)and triethylamine (29.2 g, 288.56 mmol) in toluene (390 ml) undernitrogen atmosphere was added triphosgene (15.6 g, 52.56 mmol) in onelot. The reaction was exothermic and internal temperature rose to 60° C.Later the reaction mixture was heated to 75° C. over a period of onehour and maintained at this temperature for 26 hours. The reactionmixture was cooled to room temperature, the solids filtered off, andtoluene distilled off under vacuum to get crude 18, which was vacuumdistilled to get pure 18 (10 g, 34.7%) with an m.p between 47-50° C.

EXAMPLE-19 6-[4-(2-Hydroxyethoxycarbonylamino)-phenoxy]-hexanoic acidmethyl ester (19)

6-(4-Isocyanatophenoxy)-hexanoic acid methyl ester 18 (15 g, 57 mmol)was added to ethylene glycol (50 ml) at room temp. The reaction wasexothermic and the temp. rose to 46° C. Stirring at room temp. for 16 h.was followed by addition of water (150 ml), after which crude 19 wasfiltered, dried and recrystallised from toluene to get pure 19 (12 g,84%) as a white powder with an m.p. between 69.5-71.5° C.

EXAMPLE-206-(4-{2-[4-(5-Methoxycarbonyl-pentyloxy)-phenylcarbamoyloxy]-ethoxycarbonylamino}-phenoxy)-hexanoicacid methyl ester(20)

To a mixture of 6-[4-(2-hydroxyethoxycarbonylamino)phenoxy]hexanoic acidmethyl ester 19 (5 g, 15.38 mmol) in toluene (50 ml) was added6-(4-isocyanatophenoxy)-hexanoic acid methyl ester 18 (4 g, 15.2 mmol)at room temperature and heated to 60° C. for 2 hours. Toluene wasdistilled and water (50 ml) was added. The solid was filtered and driedto give crude 20, which was purified by column chromatography on silicagel using chloroform as eluant to get pure 20 (8.5 g, 94%) as a whitepowder with an m.p. between 118-120.5° C.

EXAMPLE-21 6-(4-Nitrophenoxy)-hexanoic acid methyl ester (21)

To a mixture of 4-nitrophenol (150 g, 1.079 moles), potassium carbonate(600 g, 4.341 moles) and sodium iodide (10 g, 66.7 mmol) in anhydrousacetone (2.1 L) was added methyl 6-bromohexanoate (156 g, 746.41 mmol)with and heating to reflux for 48 hours. Acetone was distilled off andwater (2 L) was added. Crude 21 was filtered, dried and recrystallisedfrom a mixture of ethyl acetate:hexane (1:6) to get pure 21 (130 g,45.1%) as a white powder with an m.p. between 84.5.5-86.6° C.

EXAMPLE 22 (4-Nitrophenoxy)acetic acid (22)

Methyl (4-nitrophenoxy) acetate 7 (100 g, 474 mmol) was refluxed inconc. HCl (1 L) for 8 hours. The reaction mass was cooled to roomtemperature and crude 22 was filtered, dried and recrystallised from amixture of ethyl acetate:hexane (1:5) to give pure 22 (86 g, 92.1%) as awhite shining powder with an m.p. between 186-188.5° C.

EXAMPLE 23 (4-Nitrophenoxy)-acetic acid-2-hydroxy-ethyl ester (23)

Dry HCl gas was passed through a mixture of (4-nitrophenoxy) acetic acid22 (100 g, 507 mmol) and ethylene glycol (300 ml) for 1 hour. During HClgas bubbling the temperature rose to 60° C. The crude reaction mass waspoured onto ice (2 kg). Crude 23 was filtered, dried and purified bycolumn chromatography on silica gel using hexane:ethyl acetate (95:5) togive pure 23 (70 g, 57.4%) as a white powder with an m.p. between73.5-75.5° C.

¹HNMR (CDCl₃) δ 3.70 (m, 2H, CH₂), 4.28 (m, 2H,

4.56 (6m, 1H, OH), 4.80 (s, 2H, OCH₂), 7.00 (d, 2H, Ar), 8.16 (d, 2H,Ar)

EXAMPLE 24 (4—Nitrophenoxy)-aceticacid-2-[2-(4-nitrophenoxy)-acetoxy]-ethyl ester (24)

To a mixture of (4-nitrophenoxy) acetic acid 22 (80 g, 406 mmol) and(4-nitrophenoxy)-acetic acid-2-hydroxyethyl ester 23 (80 g, 332 mmol) inanhydrous dichloromethane (2 L) under nitrogen atmosphere was added asolution of 1,3-di-cyclohexyl carbodiimide (128 g, 620 mmol) inanhydrous dichloromethane (750 ml) drop wise. The reaction mixture wasstirred at room temperature for 8 hours. The solids were filtered offand dichloromethane distilled off to get crude 24. The crude 24 waspurified by column chromatography on silica gel using hexane:ethylacetate (95:5) to get pure 24 (75 grams, 54%) as a white powder with anm.p. between 138-139° C.

EXAMPLE 25 (4-Amino-phenoxy)-aceticacid-2-[2-(4-amino-phenoxy)-acetoxy]-ethyl ester (25)

(4—Nitrophenoxy)-acetic acid-2-[2-(4-nitrophenoxy)-acetoxy]-ethyl ester24 (100 g, 238 mmol) was dissolved in dry dimethyl formamide (500 ml) ina pressure vessel, palladium on carbon (5%, 22 g) was added, and themixture stirred under an atomsphere of hydrogen (4 kg) for 6 hours. Thecatalyst was removed by filtration and ice water (2.5 L) was added tothe filtrate. Crude 25 was filtered off, dried and recrystallised in amixture of methanol:chloroform (1:1) to give pure 25 (65 g, 78%) as alight brown shining powder with an m.p. between 124-125.8° C.

¹HNMR (CDCl₃) δ 4.40 (s, 2H,

4.50 (s, 2H, OCH₂), 6.54 (d, 2H, Ar), 6.70 (d, 2H, Ar), 7.26 (s, 2H,NH₂)

EXAMPLE 26 (4-Isocyanatophenoxy)-acetic acid2-[2-(4-isocyanatophenoxy)-acetoxy]-ethyl ester(26)

(4-Aminophenoxy)-acetic acid 2-[2-(4-aminophenoxy)-acetoxy]-ethyl ester25 (5 g, 14.3 mmol) were dissolved in dry dioxane (80 ml) under nitrogenatmosphere and cooled to below 20° C. A solution of triphosgene (7 g,23.6 mmol) in dry dioxane (20 ml) was added drop wise. The mixture washeated slowly to 75-80° C. and maintained for 2½ hours. The condenserwas then arranged for distillation and solvent removed by distillationat atmospheric pressure until the volume of the reaction mixture wasreduced to approximately one third. Fresh dry dioxane (50 ml) was addedand the solvent was distilled off under vacuum. The residue wasre-evaporated two times from dry dioxane to give crude 26. Crude 26 wasrecrystallised from a mixture of toluene:hexane (1:3) to give pure 26(2.6 g, 44.2%) as a white powder with an m.p. between 96-98° C.

¹HNMR (CDCl₃) δ 4.45 (s, 2H,

4.62 (s, 2H, OCH₂), 6.85 (d, 2H, Ar), 7.04 (s, 2H, Ar); IR: 2274.3 Cm⁻¹

EXAMPLE-27 [4-(2-Hydroxy-ethoxycarbonylamino)-phenoxy]-acetic acid2-{2-[4-(2-hydroxy-ethoxy carbonyl amino)-phenoxy]-acetoxy}-ethyl ester(27)

(4-Isocyanatophenoxy)-acetic acid2-[2-(4-isocyanatophenoxy)-acetoxy]-ethyl ester 26 (0.5 g, 1.21 mmol)was added to ethylene glycol (2.5 ml) at room temperature and furtherstirred for 17 hours. Water (10 ml) was added, and the solid thenfiltered, dried and recrystallised from methanol to get pure 27 (0.4 g,61.5%) as a white powder with an m.p. between 158-161° C.

EXAMPLE-28 (4-Amino-phenoxy)-acetic acid 2-hydroxy-ethyl ester (28)

(4—Nitrophenoxy)-acetic acid-2-hydroxyethyl ester 23 (1 g, 4.15 mmol)was dissolved in ethyl acetate in a pressure vessel. Palladium on carbon(5%, 0.5 g) was added and the mixture stirred under an atmosphere ofhydrogen (0.5 kg) for one hour. Catalyst was removed by filtration, theethyl acetate distilled off and hexane added. The solid product wasfiltered and dried to give pure 28 (0.2 g 22.8%) as a brown powder withan m.p. between 104-106.3° C.

EXAMPLE 29 2-(4-Nitrophenoxy)-propionic acid (29)

2-(4-Nitrophenoxy)propionic acid methyl ester 14 (50 g) and concen. HCl(500 ml) were refluxed for 8 hours. The reaction mass was cooled to roomtemperature. Crude 29 was filtered, dried and recrystallised from amixture of ethyl acetate:hexane (1:5) to give pure 29 (40 g, 85.3%) as awhite powder with an m.p. between 139-141° C.

EXAMPLE 30 2-(4-Nitrophenoxy)-propionic acid 2-hydroxy-ethyl ester (30)

Dry HCl gas was passed through a mixture of 2-(4-nitrophenoxy)-propionicacid 29 (45 g, 213 mol) and ethylene glycol (135 ml) for 1½ hours.During HCl gas bubbling the temperature rose to 60° C. The crudereaction mass was poured onto cold water (600 ml). Crude 30 wasextracted into chloroform, dried over Na₂SO₄, distilled and purified bycolumn chromatography on silica gel using hexane as eluant to give pure30 (28 g, 56.8%) as a syrup.

¹HNMR (CDCl₃) δ 1.62 (d, 3H, CH₃), 2.64 (bs, 1H, OH), 3.68 (m, 2H, CH₂),4.20 (m, 2H, CH₂), 4.82 (q, 1H, OCH), 6.85 (d, 2H, Ar), 8.05 (d, 2H, Ar)

EXAMPLE 31 2-(4-Nitrophenoxy)propionic acid2-[2-(4-nitrophenoxy)propionyloxy]ethyl ester (31)

To a mixture of 2-(4-nitrophenoxy)-propionic acid 29 (25 g, 118.5 mmol)and 2-(4-nitrophenoxy)propionic acid 2-hydroxyethyl ester 30 (25 g, 108mmol) in anhydrous dichloromethane (625 ml) under nitrogen atmospherewas added dropwise a solution of 1,3-dicyclohexyl carbodiimide (40 g,194 mmol) in anhydrous dichloromethane (250 ml). The reaction mixturewas stirred at room temperature for 8 hours. The solids were filteredoff and dichloromethane distilled off to get crude 31. The crude 31 waspurified by column chromatography on silica gel using hexane as eluantto get pure 31 (17 g, 35.1%) as a white powder with an m.p. between117.5-120.5° C.

¹HNMR (DMSO) δ 1.50(d, 3H, CH₃), 4.36 (s, 2H,

5.22 (q, 1H, OCH), 7.08 (d, 2H, Ar), 6.16 (d, 2H, Ar)

EXAMPLE 32 2-(4-Aminophenoxy)-propionic acid2-[2-(4-aminophenoxy)-propionyloxy]-ethyl ester (32)

2-(4—Nitrophenoxy)-propionic acid2-[2-(4-nitrophenoxy)propionyloxy]-ethyl ester 31 (50 g, 89.3 mmol) wasdissolved in dry dimethylformamide (400 ml) in a pressure vessel.Palladium on carbon(5%, 12.5 g) was added, and the mixture stirred underan atmosphere of hydrogen (4 kg) for 4 hours. Catalyst was removed byfiltration and ice water (3 L) was added to the filtrate. Crude 32 wasextracted into ethyl acetate, dried over Na₂SO₄, and distilled andpurified by column chromatography on silica gel using chloroform aseluant to give pure 32 (25 g, 58%) as a syrup.

¹HNMR (CDCl₃) δ 1.52 (d, 3H, CH₃), 3.30 (bs, 2H, NH₂), 4.30(s, 2H,

EXAMPLE 33 2-(4-Isocyanatophenoxy)-propionic acid2-[2-(4-isocyanatophenoxy)-propionyloxy]-ethyl ester (33)

2-(4-Aminophenoxy)-propionic acid2-[2-(4-aminophenoxy)-propionyloxy]-ethyl ester 32 (5.3 g, 13.6 mmol)was dissolved in dry dioxane (80 ml) under nitrogen atmosphere andcooled to below 20° C. A solution of triphosgene (7 g, 23.6 mmol) in drydioxane (20 ml) was added drop wise. The mixture was heated slowly to75-80° C. and maintained for 2½ hours. The condenser was then arrangedfor distillation and solvent removed by distillation at atmosphericpressure until the reaction mixture volume was reduced to approximatelyone third. Fresh dry dioxane (50 ml) was added and the solvent thendistilled off under vacuum. The residue was re-evaporated two times fromdry dioxane to give pure 33 (4 g, 66.5%) as a light brown liquid.

¹HNMR (CDCl₃) δ 1.60 (d, 3H, CH₃), 4.41 (s, 2H, COOCH₂) 4.68 (q, 1H,OCH), 6.84 (d, 2H, Ar), 7.00 (d, 2H, Ar)

EXAMPLE 34 2-[4-(2-Hydroxyethoxycarbonylamino)-phenoxy]-propionic acid2-{2-[4-(2-hydroxy-ethoxycarbonylamino)-phenoxy]-propionyloxy}-ethylester (34)

2-(4-Isocyanatophenoxy)-propionic acid2-[2-(4-isocyanatophenoxy)-propionyloxy]-ethyl ester 33 (0.5 g, 1.1mmol) was added to ethylene glycol (2.5 ml) at room temp. and stirredfor 6 hours. Water (10 ml) was added, followed by extraction into ethylacetate, drying over sodium sulphate and distilling to get crude 34,which was purified by column chromatography on silica gel usinghexane:ethyl acetate (1:1) to get pure 34 (0.1 g, 15.6%).

EXAMPLE-35 6-(4—Nitrophenoxy)-hexanoic acid (35)

6-(4-nitrophenoxy)-hexanoic acid methyl ester 21 (125 g, 468.16 mmol)was refluxed in conc. HCl (1250 ml) for 16 hours. The reaction mixturewas cooled to room temp., filtered, dried and recrystallised from amixture of ethyl acetate:hexane (1:6) to get pure 35 (95 g, 80.2%) as awhite powder with an m.p. between 104-107° C.

EXAMPLE-36 6-(4-Nitrophenoxy)-hexanoic acid 2-hydroxy-ethyl ester (36)

Dry HCl gas was passed through a mixture of 6-(4-nitrophenoxy)-hexanoicacid 35 (50 g, 197.62 mmol) and ethylene glycol (200 ml) was passed dryHCl gas for one hour. During HCl gas bubbling the temperature rose to60° C. The crude reaction mass was poured onto ice (1 kg), extracted into ethyl acetate, washed with water (2×250 ml), dried over sodiumsulphate and distilled to get crude 36, which was purified by columnchromatography on silica gel using benzene as eluant to get pure 36 (46g, 78.3) as a light yellow syrup.

EXAMPLE 38 2-(4-Nitrophenoxy)-propionic acid2-[2-(4-nitrophenoxy)-acetoxy]-ethyl ester (38)

To a mixture of [4-nitrophenoxy]-acetic acid-2-hydroxyethyl ester 23(100 grams, 410 mmol) and 2-(4-nitrophenoxy)-propionic acid 29 (95 g,450 mmol ) in anhydrous dichloromethane (1000 ml) under nitrogenatmosphere was added dropwise a solution of 1,3-dicyclohexylcarbodiimide (240 g, 1160 mmol) in anhydrous dichloromethane (600 ml).The reaction mixture was stirred at room temperature for 12 hrs. Thesolids were filtered off and dichloromethane distilled off to get crude38. The crude 38 was purified by column chromatography on silica gelusing benzene as eluant to give pure 38 (53 grams, 29%) as a yellow lowmelting solid.

¹HNMR (CDCl₃) δ 1.66 (d, 3H, CH₃), 4.40 (m, 4H, OCH₂), 4.58 (s, 2H,OCH₂), 4.81 (q, 1H, OCH), 6.92 (m, 4H, Ar), 8.16 (m, 4H, Ar)

EXAMPLE 39 2-(4-Aminophenoxy)-propionic acid2-[2-(4-aminophenoxy)-acetoxy]-ethyl ester (39)

2-(4-Nitrophenoxy)propionic acid 2-[2-(4-nitrophenoxy)acetoxy]-ethylester 38 (20 g, 50 mmol) was dissolved in dry dimethylformamide (150 ml)in a pressure vessel. Palladium on carbon (5%, 5 g) was added and themixture stirred under an atmosphere of hydrogen (4 kg) for 3 hrs. Thecatalyst was removed by filtration and ice water (1L) added to thefiltrate. Crude 39 was extracted into ethyl acetate, dried over Na₂SO₄,distilled and purified by column chromatography on silica gel usingchloroform:ethyl acetate (8:2) to give pure 39 (10 g, 58%) as a darkbrown syrup.

¹HNMR (CDCl₃) δ 1.5 (d, 3H, CH₃) 4.30 (s, 4H, OCH₂), 4.46 (s, 2H, OCH₂),4.56 (q, 1H, OCH), 6.50 (m, 4H, Ar), 6.62 (m, 4H, Ar); IR: 3363.9 Cm⁻¹

EXAMPLE 40 2-(4-Isocyanatophenoxy)-propionic acid2-[2-(4-isocyanatophenoxy)-acetoxy]-ethyl ester (40)

2-(4-Aminophenoxy)-propionic acid 2-[2-(4-aminophenoxy)-acetoxy]-ethylester 39 (5.2 g, 13.9 mmol) was dissolved in dry dioxane (80 ml) undernitrogen atmosphere and cooled to below 20° C. A solution of triphosgene(7 g, 23.6 mmol) in dry dioxane (20 ml) was added drop wise. The mixturewas heated slowly to 75-80° C. and maintained for 3 hrs. A condenser wasthen arranged for distillation and solvent removed by distillation atatmospheric pressure until the volume of the reaction mixture wasreduced to approximately one third. Fresh dry dioxane (50 ml) was addedand the solvent was distilled off under vacuum. The residue wasre-evaporated two times from dry dioxane to give 40 (2.2 g, 37.2%) as alight yellow syrup.

IR: 2270 Cm⁻¹; ¹HNMR (CDCl₃) δ 1.62 (d, 3H, CH₃) 4.40 (m, 4H, OCH₂),4.52 (s, 2H, OCH₂), 4.72 (q, 1H, OCH), 6.80 (m, 4H, Ar), 7.00 (m, 4H,Ar)

EXAMPLE 41 2-[4-(2-Hydroxyethoxycarbonylamino)-phenoxy]-propionic acid2-{2-[4-(2-hydroxy-ethoxy carbonylamino)-phenoxy]-acetoxy}-ethyl ester(41)

2-(4-Isocyanatophenoxy)-propionic acid2-[2-(4-isocyanatophenoxy)-acetoxy]-ethyl ester 40 (0.5 g, 1.17 mmol)was added to a solution of ethylene glycol (2.5 ml) in tetrahydrofuran(5 ml) at room temperature and stirred for 3 hours. The tetrahydrofuranwas distilled off under vacuum and water (10 ml) was added. Crude 41 wasextracted into ethyl acetate, washed with water (2×5ml), dried oversodium sulphate and distilled. Crude 41 was purified by columnchromatography on silica gel using chloroform at eluant to get pure 41(0.1 g, 15.6%) as a light yellow syrup.

EXAMPLE 42 [2-(4-Nitrophenoxy)-ethoxy]acetic acid methyl ester (42)

To a mixture of 4-nitrophenol (5 g, 36 mmol), anhydrous K₂CO₃ (20 g, 145mmol) and sodium iodide (2 g, 13.3 mmol) in anhydrous acetone (100 ml)was added (2-bromoethoxy)acetic acid methyl ester (11 g, 56 mmol) andthen refluxed for 24 hours. Acetone was distilled off and water (100 ml)was added. Crude 42 was filtered, dried and purified by columnchromatography on silica gel using benzene as eluant to give pure 42 (4g, 43.6%) as a white fluffy powder with an m.p. between 96-97.8° C.

¹HNMR (CDCl₃+DMSO) δ 3.72 (s, 3H, ester), 3.94 (t, 2H, OCH₂), 4.18 (s,2H, OCH₂), 4.30 (t, 2H, OCH₂), 7.08 (d, 2H, Ar), 8.18 (d, 2H, Ar)

EXAMPLE 43 [2-(4-Aminophenoxy)-ethoxy]-acetic acid methyl ester (43)

[2-(4-Nitrophenoxy)ethoxy]acetic acid methyl ester 42 (1 g, 3.9 mmol)was dissolved in anhydrous ethyl acetate (20 ml). Palladium on carbon(10%, 0.1 g) was added and the mixture stirred under a hydrogenatmosphere using a balloon for 30 mins. The catalyst was filtered, thefiltrate concentrated, hexane (3 ml) added, and the solid filtered togive 43(625 mg, 70.9%) as a light brown powder with a m.p. between51-52.5° C.

¹HNMR (CDCl₃) δ 3.04 (bs, 2H, NH₂), 3.72 (s, 3H, ester), 3.88 (t, 2H,OCH₂), 4.08 (t, 2H, OCH₂), 4.20 (s, 2H, OCH₂), 6.58 (d, 2H, Ar), 6.70(d, 2H, Ar)

EXAMPLE 44 (4-Nitrophenoxy)-acetic acid methoxycarbonylmethyl ester (44)

To a mixture of (4-nitrophenoxy) acetic acid 22 (150 g, 761.4 mmol) andtriethylamine (85 g, 840 mmol) in acetone (750 ml) was added methylchloroacetate (91.6 g, 844 mmol) drop wise and stirred under reflux for8 hours. Solids were filtered off and poured onto cold 5% sodiumbicarbonate solution (4 L). Crude 44 was filtered, dried andrecrystallised from chloroform:hexane (1:6) to get pure 44 (186 g,90.8%) as a white powder with an m.p. between 88-90° C.

¹H NMR (CDCl₃) δ 3.80 (s, 3H, Ester), 4.75 (s, 2H, OCH₂), 4.88 (s, 2H,OCH₂), 7.02 (d, 2H, Ar), 8.22 (d, 2H, Ar)

EXAMPLE 45 (4-Aminophenoxy)-acetic acid methoxycarbonylmethyl ester (45)

(4-Nitrophenoxy)-acetic acid methoxycarbonyl methyl ester 44 (20 g, 74.3mmol) was dissolved in dimethyl formamide (100 ml) in a pressure vessel.Palladium on carbon (5%, 8 g) was added, and the mixture stirred underan atmosphere of hydrogen (4 kg) for 2 hours. The catalyst was removedby filtration and ice water (400 ml) was added to the filtrate. Crude 45was extracted into ethyl acetate, dried over Na₂SO₄ and distilled. Crude45 was then recrystallised from chloroform:hexane (1:6) to get pure 45(13 g, 73%) as a light brown shining powder with an m.p. between76.5-78.5° C.

¹H NMR (CDCl₃) δ 3.32 (bs, 2H, NH₂), 3.76 (s, 3H, Ester), 4.70 (s, 2H,OCH₂), 4.74 (s, 2H, OCH₂), 6.60 (d, 2H, Ar), 6.74 (d, 2H, Ar)

EXAMPLE 46 (4-Cyanatophenoxy)-acetic acid methoxycarbonyl methyl ester(46)

(4-Aminophenoxy)-acetic acid methoxycarbonyl methyl ester 45 (10 g,41.84 mmol) was dissolved in dry dioxane (200 ml) under nitrogenatmosphere and cooled below 20° C. A solution of triphosgene (10.5 g,35.38 mmol) in dry dioxane (50 ml) was added drop wise. The mixture washeated slowly to 70-75° C. and maintained for 2½ hours. The condenserwas then arranged for distillation and the solvent removed bydistillation at atmospheric pressure until the volume of the reactionmixture was reduced to approximately one third. Fresh dry dioxane (125ml) was added and the solvent distilled off under vacuum. The residuewas re-evaporated two times from dry dioxane to give pure 46 (10 g,90.2%) as a liquid.

IR: 2275.6 cm⁻¹; ¹H NMR (CDCl₃) δ 3.80 (s, 3H, Ester), 4.74 (s, 4H,CH₂×2), 6.88 (d, 2H, Ar), 7.06 (d, 2H, Ar)

EXAMPLE 47 [4-(2-Hydroxyethoxycarbonylamino)-phenoxy]-acetic acidmethoxycarbonyl methyl ester (47)

To a solution of (4-cyanatophenoxy)acetic acid methoxycarbonyl methylester 46 (5 g 18.85 mmol) in dry tetrahydrofuran (20 ml) was addedethylene glycol (30 ml) with stirring at room temperature for 30minutes. The reaction mixture was poured onto ice water (100 ml) andcrude 47 was extracted into ethyl acetate, dried over sodium sulphateand distilled. Crude 47 was purified by column chromatography on silicagel using chloroform as eluant to get pure 47 (2 g, 32.4%) with an m.p.between 79-82° C.

¹H NMR (CDCl₃) δ 3.76 (s, 3H, Ester), 3.80 (t, 2H, CH₂), 4.25 (m, 2H,CH₂), 4.70 (s, 2H, CH₂), 4.72 (s, 2H, CH₂), 6.84 (d, 2H, Ar), 7.02 (s,1H, NH), 7.26 (d, 2H, Ar)

EXAMPLE 48 (4-Acetylaminophenoxy)acetic acid methoxycarbonyl methylester (48)

Acetyl chloride was added dropwise to a mixture of 4-aminophenoxyaceticacid methoxycarbonyl methyl ester 45 (3 g, 12.5 mmol) and triethylamine(3.8 g, 37.5 mmol) in acetone (30 ml) at 0° C. and stirred at roomtemperature for 12 hrs. The solids were filtered, the acetone distilledoff and cold water (15 ml) was added. Crude 48 was extracted intochloroform, washed with 5% sodium bicarbonate solution (2×5 ml), water(2×5 ml), dried over sodium sulphate and distilled. Crude 48 wasrecrystallised from a mixture of chloroform:hexane (1:6) to give pure 48(3 g, 85%) as an off-white powder. M.p: 98.6-101.5° C.

¹H NMR (CDCl₃) δ 2.20 (s, 3H, COCH₃), 3.78 (s, 3H, ester), 4.70 (s, 4H,CH₂×2), 6.82 (d, 2H, Ar), 7.18 (s, 1H, NH), 7.35 (d, 2H, Ar)

EXAMPLE 49 [4-(2-Benzyloxyacetylamino)-phenoxy]-acetic acid methyl ester(49)

To a mixture of (4-aminophenoxy)-acetic acid methyl ester 3 (20 g, 110.5mmol) and benzyloxy acetic acid (20.4 g, 123 mmol) in anhydrousdichloromethane (200 ml) under nitrogen atmosphere was added dropwise asolution of 1,3-dicyclohexyl carbodiimide (63.2 g, 306 mmol) inanhydrous dichloromethane (80 ml) then stirred at room temp. for 12hours. The solids were filtered off, the dichloromethane was washed with5% sodium bicarbonate solution (100 ml), water (100 ml) added, and thesolids dried over sodium sulphate and distilled to get crude 49. Crude49 was purified by column chromatography on silica gel using benzene aseluant to get pure 49 (25 g, 68.9%) as a white powder with an m.p.between 76-77.5° C.

¹H NMR (CDCl₃) δ 3.82 (s, 3H, ester), 4.10 (s, 2H, CH₂), 4.62 (s, 2H,CH₂), 4.66 (s, 2H, CH₂), 6.88 (d, 2H, Ar), 7.38 (m, 5H, Ar), 7.46 (d,2H, Ar), 8.24 (bs, 1H, NH)

EXAMPLE 50 [4-(2-Hydroxyacetylamino)-phenoxy]-acetic acid methyl ester(50)

[4-(2-Benzyloxyacetylamino)phenoxy]acetic acid methyl ester 49 (25 g, 76mmol) was dissolved in methanol (450 ml) in a pressure vessel. Palladiumon carbon (5%, 10 g) was added and the mixture stirred under a hydrogenatmosphere (2 kg) for 5 hrs. Catalyst was removed by filtration andmethanol distilled off. Crude 50 was recrystallised in chloroform:hexane(1:6) to give pure 50 (14 g) as a white powder with an m.p. between147.5-150° C.

¹H NMR (CDCl₃+DMSO-d₆): δ 3.74 (s, 3H, ester), 3.96 (d, 2H, CH₂OH), 4.64(s, 2H, OCH₂), 5.48 (t, 1H, OH), 6.80 (d, 2H, Ar), 7.54 (d, 2H, Ar) 9.2(bs, 1H, NH)

EXAMPLE 51 2-[4-(2-Benzyloxyacetylamino)-phenoxy]-propionic acid methylester (51)

To a mixture of 2-(4-aminophenoxy)-propionic acid methyl ester 10 (20grams, 102.5 mmol) and triethylamine (23 ml, 165 mmol) in acetone (120ml) at 0° C. was added dropwise benzyloxy acetyl chloride (28 g, 152mmol) followed by stirring at room temp for 12 hours. The solids werefiltered off, acetone distilled off, and water (100 ml) added. Crude 51was extracted into chloroform, washed with 5% sodium bicarbonate (2×100ml) and water (200 ml), then dried over sodium sulphate and distilled.Crude 51 was purified by column chromatography on silica gel usingbenzene as eluant to get pure 51 (21 g, 59.8%) as a light brown powderwith an m.p. between 67-70° C.

¹H NMR (CDCl₃) δ 1.60 (d, 3H, CH₃), 3.72 (s, 3H, Ester), 4.02 (s, 2H,CH₂), 4.62 (s, 2H, CH₂), 4.68 (q, 1H, CH), 6.76 (d, 2H, Ar), 7.30 (m,5H, Ar), 7.42 (d, 2H, Ar), 8.18 (s, 1H, NH)

EXAMPLE 52 2-[4-(2-Hydroxyacetylamino)-phenoxy]-propionic acid methylester (52)

2-[4-(2-Benzyloxyacetylamino)-phenoxy]-propionic acid methyl ester 51(15 gm, 43.7 mmol) was dissolved in methanol (150 ml) in a pressurevessel. Palladium on carbon (5%, 8 g) was added and the mixture stirredunder a hydrogen atmosphere (2.5 kg) for 10 hrs. Catalyst was removed byfiltration and the methanol distilled off. The crude 52 wasrecrystallised in chloroform:hexane (1:6) to give pure 52 (4 g, 36.3%)as a white powder with an m.p. between 111-112.6° C.

¹H NMR (CDCl₃) δ 1.60 (d, 3H, CH₃), 3.44 (bt, 1H, OH), 3.78 (s, 3H,Ester), 4.14 (d, 1H, CH₂OH), 4.72 (q, 1H, CH), 6.80 (d, 2H, Ar), 7.44(d, 2H, Ar), 8.30 (s, 1H, NH

EXAMPLE 53 6-[4-(2-Benzyloxy-acetylamino)-phenoxy]-hexanoic acid methylester (53)

To a mixture of 6-(4-aminophenoxy)-hexanoic acid methyl ester 17 (25 g,105 mmol) and triethylamine (21.4 g, 211.6 mmol) in acetone (200 ml) at0° C. was added dropwise benzyloxy acetyl chloride (25 g, 135.5 mmol)followed by stirring at room temp. for 12 hrs. The solids were filteredoff, acetone distilled off and water (100 ml) added. Crude 53 wasextracted into chloroform, washed with 5% sodium bicarbonate solution(2×100 ml), then water (100 ml), dried over sodium sulphate anddistilled. Crude 53 was purified by column chromatography on silica gelusing benzene as eluant to get pure 53 (9 g, 22.2%), an off-white powderwith a m.p. between 46-49° C.

¹H NMR (CDCl₃) δ 1.52 (m, 2H, CH₂), 1.72 (m, 4H, CH₂×2), 2.32 (t, 2H,CH₂), 3.68 (s, 3H, Ester), 3.92 (t, 2H, CH₂), 4.10 (s, 2H, CH₂), 4.68(s, 2H, CH₂), 6.82 (d, 2H, Ar), 8.20 (s, 1H, NH)

EXAMPLE 54 6-[4-(2-Hydroxyacetylamino)-phenoxy]-hexanoic acid methylester (54)

6-[4-(2-Benzyloxyacetylamino)-phenoxy]-hexanoic acid methyl ester 53 (1grams, 2.6 mmol) was dissolved in methanol (10 ml) in a pressure vessel.Palladium on carbon (5%, 250 mg) was added and the mixture stirred undera hydrogen atmosphere (2 kg) for 5 hrs. Catalyst was removed byfiltration and methanol distilled off. Crude 54 was recrystallised inchloroform:hexane (1:6) to get pure 54 (0.5 g, 65.3%) as a white powderwith an m.p. between 91.5-94° C.

¹H NMR (CDCl₃) δ 1.45 (m, 2H, CH₂), 1.62 (m, 4H, CH₂×2), 2.36 (t, 2H,CH₂), 3.02 (t, 2H, CH₂), 3.02 (t, 1H, OH), 3.68 (s, 3H, Ester), 3.92 (t,2H, CH₂), 4.22 (d, 2H, CH₂), 6.84 (d, 2H, Ar), 7.46 (d, 2H, Ar), 8.24(bs, 1H, NH).

EXAMPLE 55 [4-(2-Hydroxyacetylamino)-phenoxy]-acetic acidmethoxycarbonyl methyl ester (55)

To a mixture of (4-aminophenoxy)-acetic acid methoxycarbonyl methylester 45 (5 g, 20.9 mmol) and triethylamine (8.8 ml, 63.1 mmol) inacetone (50 ml) at 0° C. was added dropwise benzyloxy acetyl chloride(5.8 g, 31.4 mmol), followed by stirring at room temp. for 20 hrs. Thesolids were filtered off, the acetone distilled off and water (50 ml)added. Crude 55 was extracted into chloroform, washed with 5% sodiumbi-carbonate (2×50 ml) and water (2×50 ml), dried over sodium sulphateand distilled. Crude 55 was purified by column chromatography on silicagel using chloroform as eluant to get pure 55 (5 g, 61.7%) as a lightbrown powder with an m.p, between 66.5-69.5° C.

¹H NMR (CDCl₃) δ 3.78 (s, 3H, Ester), 4.06 (s, 2H, CH₂), 4.64 (s, 2H,CH₂), 4.70 (s, 4H, CH₂×2), 6.86 (d, 2H, Ar), 7.34 (m, 5H, Ar), 7.48 (d,2H, Ar), 8.18 (bs, 1H, NH),

EXAMPLE 56 [4-(2-Hydroxyacetylamino)-phenoxy]-acetic acidmethoxycarbonyl methyl ester (56)

[4-(2-Hydroxyacetylamino)-phenoxy]-acetic acid methoxycarbonyl methylester 55 (2 g) was dissolved in methanol (20 ml) in a pressure vessel.Palladium on carbon (5%, 1 g) was added and the mixture stirred under ahydrogen atmosphere (2.5 kg) for 10 hrs. The catalyst was removed byfiltration and the methanol distilled off. Crude 56 was purified bycolumn chromatography on silica gel using chloroform as eluant to givepure 56 (0.5 g, 32.5%) as a white powder with an m.p. between 92-95° C.

¹H NMR (CDCl₃+DMSO,d₆) δ 3.75 (s, 3H, Ester), 3.88 (d, 2H, CH₂OH), 4.74(s, 2H, CH₂), 4.78 (s, 2H, CH₂),5.50(t,1H,OH), 6.84(d,2H,Ar),7.58(d,2H,Ar), 9.02(s, 1H,NH)

EXAMPLE 57 [4-(6-Benzyloxyhexanoylamino)-phenoxy]-acetic acid methylester (57)

To a mixture of (4-aminophenoxy)-acetic acid methyl ester 3 (20 g, 110.5mmol) and benzyloxy hexanoic acid (50 g, 225.22 mmol) in anhydrousdichloromethane (300 ml) at 0° C. under nitrogen atmosphere was addeddropwise a solution of 1,3-dicyclohexyl carbodiimide (80 g, 387.73 mmol)in anhydrous dichloromethane (100 ml). The reaction mixture was stirredat room temperature for 16 hours. The solids were filtered off, thedichloromethane was washed with 5% sodium bicarbonate solution (2×100ml), then water (2×100 ml), dried over sodium sulphate and distilled toget crude 57. Crude 57 was purified by column chromatography on silicagel using chloroform as eluant to give 24 grams of[4-(6-Benzyloxyhexanoylamino)-phenoxy]-acetic acid methyl ester whichwas further purified by recrystallising in chloroform:hexane (1:6) togive pure 57 (20 g, 47%) as a white powder with an m.p. between 64.6-67°C.

¹H NMR (CDCl₃) δ 1.48 (m, 2H, CH₂), 1.68 (m, 4H, CH₂), 2.30 (t, 2H,CH₂), 3.44 (t, 2H, CH₂), 3.78 (s, 3H, ester), 4.44 (s, 2H, CH₂), 4.56(s, 2H, CH₂), 6.74 (d, 2H, Ar), 7.30 (m, 5H, Ar), 7.35 (d, 2H, Ar), 7.50(s, 1H, NH).

EXAMPLE 58 [4-(6-Hydroxyhexanoylamino)-phenoxy]-acetic acid methyl ester(58)

[4-(6-Benzyloxyhexanoylamino)-phenoxy]-acetic acid methyl ester 57 (24grms, 62.33 mmol) was dissolved in a mixture of methanol (200 ml) anddimethyl formamide (50 ml) in a pressure vessel. Palladium on carbon(5%, 15 g) was added and the mixture stirred under an atmosphere ofhydrogen (4 kg) for 24 hours. Catalyst was removed by filtration, andthe solvents distilled off under vacuum. Crude 58 was purified by columnchromatography on silica gel using chloroform as eluant to get pure 58(4.5 g, 24.4%) as a white powder with an m.p. between 87.5-90.4° C.

¹H NMR (CDCl₃+DMSO-d₆) δ 1.40 (m, 4H, CH₂), 1.60 (m, 2H, CH₂), 2.20 (t,2H, CH₂),3.40 (t, 2H, CH₂), 3.68 (s, 3H, ester), 3.94 (bs, 1H, OH), 4.50(s, 2H, CH₂), 6.68 (d, 2H, Ar), 7.42 (d, 2H, Ar), 9.30 (s, 1H, NH).

EXAMPLE 59 2-[4-(6-Benzyloxyhexanoylamino)-phenoxy]-propionic acidmethyl ester (59)

To a mixture of 2-(4-aminophenoxy)-propionic acid methyl ester 10 (20grams, 102.44 mmol) and benzyloxy hexanoic acid (57 g, 256.43 mmol) inanhydrous dichloromethane (250 ml) at 0° C. under nitrogen atmospherewas added dropwise a solution of 1,3-dicyclohyoyl carbodiimide (74 g,358.64 mmol) in anhyd. dichloromethane (75 ml). The reaction mixture wasstirred at room temp. for 20 hrs. Solids were filtered off, thedichloromethane was washed with 5% sodium bicarbonate (2×100 ml), thenwater (2×100 ml), dried over sodium sulphate, and distilled to get crude59. Crude 59 was purified by column chromatography on silica gel usingchloroform as eluant to get pure 59 (15 g, 36.7%) as a light pink powderwith an m.p. between 73-76.5° C.

¹H NMR (CDCl₃) δ 1.45 (m, 2H, CH₂), 1.60 (d, 3H, CH₃), 1.70 (m, 4H,CH₂),2.45 (t, 2H, CH₂), 3.45 (t, 2H, CH₂), 3.72 (s, 3H, Ester), 4.46 (s,2H, CH₂), 4.66 (q, 1H, CH), 6.70 (d, 2H, Ar), 7.24 (m, 5H, Ar), 7.30 (d,2H, Ar), 7.54 (s, 1H, NH)

EXAMPLE 60 2-[4-(6-Hydroxyhexanoylamino)-phenoxy]-propionic acid methylester (60)

2-[4-(6-Benzyloxyhexanoylamino)-phenoxy]-propionic acid methyl ester 59(15 g, 37.59 mmol) was dissolved in methanol (150 ml) in a pressurevessel. Palladium on carbon (50% wet, 5%, 15 g) was added and themixture stirred under hydrogen atmosphere (4 kg) for 16 hrs. Catalystwas removed by filtration and methanol distilled off. Crude 60 waspurified by column chromatography on silica gel using chloroform aseluant to get pure 60 (6 g, 51.6%) as a white powder with an m.p between62-64.5° C.

¹H NMR (CDCl₃) δ 1.40 (m, 6H, CH₂), 1.54 (d, 3H, CH₃), 2.21 (t,2H, CH₂),3.48(t,2H), CH₂), 3.70(s,3H,Ester), 4.66(q,1H,CH), 6.68(d,2H,Ar),7.36(d,2H,Ar), 8.66(s, 1H,NH)

EXAMPLE 61 6-[4-(6-Benzyloxyhexanoylamino)-phenoxy]-hexanoic acid methylester (61)

To a mixture of 6-(4-aminophenoxy)-hexanoic acid methyl ester 17 (25grams, 105.48 mmol) and benzyloxyhexanoic acid (37.5 g, 168.7 mmol) inanhyd. dichloromethane (250 ml) at 0° C. under nitrogen atmosphere wasadded dropwise a solution of 1,3-dicyclohexyl carbodiimide (55 g, 266.56mmol) in anhydrous dichloromethane (60 ml). The reaction mixture wasstirred at room temperature for 16 hs. Solids were filtered off, thedichloromethane was washed with 5% sodium bicarbonate solution (2×100ml), then water (2×100 ml), dried over sodium sulphate and distilled toget crude 61. Crude 61 was purified by column chromatography on silicagel using benzene:hexane (1:1) to get pure 61 (28 g, 60.2%) as a whitepowder with an m.p, between 64-65.6° C.

¹H NMR (CDCl₃) δ 1.48 (m, 2H, CH₂), 1.70 (m, 1OH, CH₂), 2.30 (m, 2H,CH₂), 3.48 (t, 2H, CH₂), 3.68 (s, 3H, Ester), 3.88 (t, 2H, CH₂), 4.44(s, 2H, CH₂), 6.72 (d, 2H, Ar), 7.30 (m, 8H, Ar & NH)

EXAMPLE 62 6-[4-(6-Hydroxyhexanoylamino)-phenoxy]-hexanoic acid methylester (62)

6-[4-(6-Benzyloxyhexanoylamino)-phenoxy]-hexanoic acid methyl ester 61(10 g, 22.67 mmol) was dissolved in methanol (100 ml) in a pressurevessel. Palladium on carbon (5%, 6 grm) was added and the mixturestirred under a hydrogen atmosphere (4 kg) for 20 hrs. The catalyst wasremoved by filtration, and methanol distilled off. Crude 62 was purifiedby column chromatography on silica gel using chloroform as eluant togive pure 62 (5 g, 62.8%) as a white powder with a m.p. between 73-75.5°C.

¹H NMR (CDCl₃) δ 1.40 to 1.80 (m, 12H, CH₂), 2.36 (m, 4H, CH₂), 3.58 (t,2H, CH₂), 3.64 (s, 3H, Ester), 3.88 (t, 2H, CH₂), 6.72 (d, 2H, Ar),7.26(d,2H,Ar), 7.40(s, 1H,NH).

EXAMPLE 63 [4-(6-Benzyloxyhexanoylamino)phenoxy]acetic acidmethoxycarbonyl methyl ester (63)

To a mixture of (4-aminophenoxy)acetic acid methoxycarbonyl methyl ester43 (15 g, 62.76 mmol) and benzyloxyhexanoic acid (21 g, 94.47 mmol), inanhydrous dichloromethane (300 ml) at 0° C. under nitrogen atmospherewas added dropwise a solution of 1,3-dicyclohexyl carbodiimide (39 g,189 mmol). The reaction mixture was stirred at room temp. for 18 hrs.The solids were filtered off, the dichloromethane was washed with 5%sodium bicarbonate solution (2×75 ml), then water (2×75 ml), dried oversodium sulphate, and distilled to give crude 63. Crude 63 was purifiedby column chromatography on silica gel using chloroform as eluant to getpure 63 (15 g, 53.9%) as a white powder with an m.p. between 71-73° C.

¹H NMR (CDCl₃) δ 1.44 (m, 2H, CH₂), 1.66 (m, 4H, CH₂), 2.30 (t, 2H,CH₂), 3.44 (t, 2H, CH₂), 3.74 (s, 3H, Ester), 4.48 (s, 2H, CH₂), 4.70(s, 4H, CH₂), 6.80 (d, 2H, Ar), 7.30 (m, 8H, Ar & NH)

EXAMPLE 64 [4-(6-Hydroxyhexanoylamino)phenoxy]acetic acidmethoxycarbonyl methyl ester (64)

[4-(6-Benzyloxyhexanoylamino)-phenoxy]-acetic acid methoxycarbonylmethyl ester 63 (13 g, 29.34 mmol) was dissolved in dimethylformamide(100 ml) in a pressure vessel. Palladium on carbon (5%, 10 g) was addedand the mixture stirred under a hydrogen atmosphere (4 kg) for 20 hrs.Catalyst was removed by filtration and dimethylformamide distilled offunder vacuum. Ice water (100 ml) was added and extracted withchloroform, dried over sodium sulphate, and distilled to give crude 64.Crude 64 was purified by column chromatography on silica gel usingchloroform as eluant to give 6 g of solid, which was further purified byrecrystallising in chloroform: hexane (1:6) to get pure 64 (4 g, 38.6%)as a light pink powder with an m.p. between 68-70.5° C.

¹H NMR (CDCl₃) δ 1.44 (m, 2H, CH₂), 1.58 (m, 2H, CH₂), 1.74 (m, 2H,CH₂), 2.30 (t, 2H, CH₂), 2.38 (bs, 1H, OH), 3.56 (t, 2H, CH₂), 3.78 (s,3H, Ester), 4.70 (s, 4H, CH₂), 6.80 (d, 2H, Ar), 7.48 (d, 2H, Ar), 8.74(s, 1H, NH).

In Vitro Hydrolysis of Functionalized Phenolics

Selected compounds were examined for the rate of hydrolysis byconducting in vitro hydrolysis studies at reflux temp. (100° C.). Foreach experiment, 500 mg of a functionalized compound and 50 ml of pH 7.4buffer solution (purchased from Aldrich Chemical) were charged into a100 ml round bottom flask fitted with a condenser and the contents wererefluxed. In vitro hydrolysis of the functionalized phenolics wasmonitored by thin layer chromatography (TLC) using correspondingstarting material (original phenolic) as a control. In vitro hydrolysiswas continued at reflux until the functionalized molecule hydrolyzed tothe starting phenolic compound.

EXAMPLE 65 (4-Aminophenoxy)-acetic acid methoxycarbonyl methyl ester(EXAMPLE-45) was hydrolyzed in 3 hours under the above conditions.

EXAMPLE 66 (4-Acetylaminophenoxy)acetic acid methoxycarbonyl methylester (EXAMPLE 48) was hydrolyzed in 8 hours under the above conditions

EXAMPLE 67

(4-Aminophenoxy)-acetic acid-2-[2-(4-aminophenoxy)-acetoxy]-ethyl ester(Example 25) was hydrolyzed in 11.5 hours under the above conditions.

EXAMPLE 68

2-(4-Amino-phenoxy)-propionic acid2-[2-(4-amino-phenoxy)-propionyloxy]-ethyl ester (EXAMPLE-32) washydrolyzed in 40 hours under the above conditions.

This data indicate that the polymers derived from the functionalizedaminophenolics should hydrolyze. Therefore, using the functionalizedaminophenolics, one can develop polymers with controlled hydrolysisprofiles.

The foregoing examples and description of the preferred embodimentsshould be taken as illustrating, rather than as limiting, the presentinvention as defined by the claims. As would be readily appreciated,numerous combinations of the features set forth above can be utilizedwithout departing from the present invention as set forth in the claims.Such variations are not regarded as a departure from the spirit andscope of the invention, and all such modifications are intended to beincluded within the scope of the following claims.

1. An absorbable polymer polymerized from at least one monomer compoundselected from the group consisting of:

Wherein each X represents a member independently selected from the groupconsisting of: —CH₂COO— (glycolic acid moiety), —CH(CH₃)COO— (lacticacid moiety), —CH₂CH₂OCH₂COO— (dioxanone moiety), —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety), —(CH₂)_(y)COO— where y is one of the numbers2,3,4 or 6-24 inclusive, and —(CH₂CH₂O)_(z′)CH₂COO— where z′ is aninteger between 2 and 24, inclusive; each Y represents a memberindependently selected from the group consisting of: —COCH₂O— (glycolicester moiety), —COCH(CH₃)O— (lactic ester moiety), —COCH₂OCH₂CH₂O—(dioxanone ester moiety), —COCH₂CH₂CH₂CH₂CH₂O— (caprolactone estermoiety), —CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24inclusive, —CO CH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and24, inclusive; R′ is hydrogen, benzyl or an alkyl group, the alkyl groupbeing either straight-chained or branched; p is an integer between 1 and4, inclusive; and Rn represents one or more members selected from thegroup consisting of H, alkoxy, benzyloxy, aldehyde, halogen, carboxylicacid and —NO₂, which is attached directly to an aromatic ring orattached through an aliphatic chain.
 2. A polymer according to claim 1wherein each X is independently selected from the group consisting of:—CH₂COO— (glycolic acid moiety), —CH(CH₃)COO— (lactic acid moiety),—CH₂CH₂OCH₂COO— (dioxanone moiety), and —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety); and each Y is independently selected from thegroup consisting of: —COCH₂O— (glycolic ester moiety); —COCH(CH₃)O—(lactic ester moiety); —COCH₂OCH₂ CH₂O— (dioxanone ester moiety); and—COCH₂CH₂CH₂CH₂CH₂O— (caprolactone ester moiety).
 3. A polymer accordingto claim 1 polymerized from at least one compound selected from thegroup consisting of aminophenols, aminosalicylic acids, and aminobenzoicacids.
 4. A polymer according to claim 1, wherein said polymer is apolyamide, polyester urethane or a polyester amide.
 5. The polymer ofclaim 4, wherein said monomer compound comprises two active sites forpolymerization independently selected from the group consisting of (a) acarboxyl group and an amino group, (b) a hydroxyl group and an aminegroup and (c) a carboxylic acid and an isocyanate group.
 6. The polymerof claim 5, wherein said two active sites are a carboxyl group and anamino group.
 7. The polymer of claim 4, wherein said two active sitesare a hydroxyl group and an amine group, and said monomer compound isreacted with a dicarboxylic acid to form a polyesteramide.
 8. Thepolymer of claim 4, wherein said two active sites are a carboxylic acidand an isocyanate group, and said monomer compound is reacted with adihydroxy compound to form a polyester urethane.
 9. An articlecomprising a metal or polymeric substrate for mammalian tissue contactand having thereon a coating, wherein said coating comprises at leastone polymer according to claim
 4. 10. The article of claim 9, whereinsaid article is an implantable medical device.
 11. An implantablemedical device comprising at least one polymer according to claim
 4. 12.A molded article characterized by being prepared from at least onepolymer according to claim
 4. 13. A controlled drug delivery systemcharacterized by at least one polymer according to claim 4, physicallyadmixed with a biologically or pharmacologically active agent.
 14. Acontrolled drug delivery system characterized by a biologically orpharmacologically active agent physically embedded or dispersed into apolymeric matrix formed from at least one polymer according to claim 4.15. A tissue scaffold having a porous structure for the attachment andproliferation of cells, either in vitro or in vivo, characterized bybeing formed from one least one polymer according to claim
 4. 16. Thepolymer of claim 4, wherein said polymer comprises reactive end groups.17. The polymer of claim 16, wherein each reactive end group isindependently selected from the group consisting of isocyanates,epoxides, and acrylates.
 18. A polymer according to claim 4, whereinsaid polymer is polymerized on at least one end with at least onelactone monomer selected from the group consisting of glycolide,lactide, p-dioxanone, trimethylene carbonate and caprolactone.
 19. Animplantable medical device comprising at least one polymer according toclaim
 18. 20. A molded article characterized by being prepared from atleast one polymer according to claim
 18. 21. A controlled drug deliverysystem characterized by at least one polymer according to claim 18,physically admixed with a biologically or pharmacologically activeagent.
 22. A controlled drug delivery system characterized by abiologically or pharmacologically active agent physically embedded ordispersed into a polymeric matrix formed from at least one polymeraccording to claim
 18. 23. A tissue scaffold having a porous structurefor the attachment and proliferation of cells, either in vitro or invivo, characterized by being formed from at least one polymer accordingto claim
 18. 24. An absorbable polyamide polymer polymerized from atleast one monomer compound of the formula:

Wherein each X represents a member independently selected from the groupconsisting of: —CH₂COO— (glycolic acid moiety); —CH(CH₃)COO— (lacticacid moiety); —CH₂CH₂OCH₂COO— (dioxanone moiety); —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety); —(CH₂)_(y)COO— where y is one of the numbers2,3,4 and 6-24 inclusive; and —(CH₂CH₂O_(z′)CH₂COO— where z′ is aninteger between 2 and 24, inclusive; each Y represents a memberindependently selected from the group consisting of: —COCH₂O— (glycolicester moiety); —COCH(CH₃)O— (lactic ester moiety); —COCH₂OCH₂CH₂O—(dioxanone ester moiety); —COCH₂CH₂CH₂CH₂CH₂O— (caprolactone estermoiety); —CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24inclusive; and —COCH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and24, inclusive; each R′ is independently a hydrogen, benzyl or an alkylgroup, the alkyl group being either straight-chained or branched; each pis independently an integer between 1 and 4, inclusive; Z is O or NH;and Rn represents one or more members selected from the group consistingof H, alkoxy, benzyloxy, aldehyde, halogen, carboxylic acid and —NO₂,which is attached directly to an aromatic ring or attached through analiphatic chain.
 25. A polymer according to claim 24 wherein each X isindependently selected from group consisting of: —CH₂COO— (glycolic acidmoiety), —CH(CH₃)COO— (lactic acid moiety), —CH₂CH₂OCH₂COO— (dioxanonemoiety), and —CH₂CH₂CH₂CH₂CH₂COO— (caprolactone moiety); and each Y isindependently selected from the group consisting of: —COCH₂O— (glycolicester moiety); —COCH(CH₃)O— (lactic ester moiety); —COCH₂OCH₂ CH₂O—(dioxanone ester moiety); and —COCH₂CH₂CH₂CH₂CH₂O— (caprolactone estermoiety).
 26. An polymer according to claim 24, wherein said monomercomound is an aminophenol, aminosalicylic acid or an aminobenzoic acid.27. An article comprising a metal or polymeric substrate for mammaliantissue contact and having thereon a coating, wherein said coatingcomprises at least one polymer according to claim
 24. 28. The article ofclaim 27, wherein said article is an implantable medical device.
 29. Animplantable medical device comprising at least one polymer according toclaim
 24. 30. A molded article characterized by being prepared from atleast one polymer according to claim
 24. 31. A controlled drug deliverysystem characterized by at least one polymer according to claim 24,physically admixed with a biologically or pharmacologically activeagent.
 32. A controlled drug delivery system characterized by abiologically or pharmacologically active agent physically embedded ordispersed into a polymeric matrix formed from at least one polymeraccording to claim
 24. 33. A tissue scaffold having a porous structurefor the attachment and proliferation of cells, either in vitro or invivo, characterized by being formed from one least one polymer accordingto claim
 24. 34. The polymer of claim 24, wherein said polymer comprisesreactive end groups.
 35. The polymer of claim 34, wherein each reactiveend group is independently selected from the group consisting ofisocyanates, epoxides, and acrylates.
 36. The polymer according to claim24, wherein said polymer is polymerized on at least one end with atleast one lactone monomer selected from the group consisting ofglycolide, lactide, p-dioxanone, trimethylene carbonate andcaprolactone.
 37. An implantable medical device comprising at least onepolymer according to claim
 36. 38. A molded article characterized bybeing prepared from at least one polymer according to claim
 36. 39. Acontrolled drug delivery system characterized by at least one polymeraccording to claim 36, physically admixed with a biologically orpharmacologically active agent.
 40. A controlled drug delivery systemcharacterized by a biologically or pharmacologically active agentphysically embedded or dispersed into a polymeric matrix formed from atleast one polymer according to claim
 36. 41. A tissue scaffold having aporous structure for the attachment and proliferation of cells, eitherin vitro or in vivo, characterized by being formed from at least onepolymer according to claim
 36. 42. An absorbable polyurethane preparedfrom at least one monomer compound of the formula:

Wherein each X represents a member independently selected from the groupconsisting of: —CH₂COO— (glycolic acid moiety); —CH(CH₃)COO— (lacticacid moiety); —CH₂CH₂OCH₂COO— (dioxanone moiety); —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety); —(CH₂)_(y)COO— where y is one of the numbers2,3,4 and 6-24 inclusive; and —(CH₂CH₂O)_(z′)CH₂COO— where z′ is aninteger between 2 and 24, inclusive; each Y represents a memberindependently selected from the group consisting of: —COCH₂O— (glycolicester moiety); —COCH(CH₃)O— (lactic ester moiety); —COCH₂OCH₂ CH₂O—(dioxanone ester moiety); —COCH₂CH₂CH₂CH₂CH₂O— (caprolactone estermoiety); —CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24inclusive; and —CO CH₂O(CH₂CH₂O)_(n)— where n is an integer between 2and 24, inclusive; each R′ is hydrogen, benzyl or an alkyl group, thealkyl group being either straight-chained or branched; each p isindependently an integer between 1 and 4, inclusive; Z is O or NH; andRn represents one or more members selected from the group consisting ofH, alkoxy, benzyloxy, aldehyde, halogen, carboxylic acid and —NO₂, whichis attached directly to an aromatic ring or attached through analiphatic chain.
 43. A polymer according to claim 42 wherein each X isindependently selected from the group consisting of: —CH₂COO— (glycolicacid moiety), —CH(CH₃)COO— (lactic acid moiety), —CH₂CH₂OCH₂COO—(dioxanone moiety), and —CH₂CH₂CH₂CH₂CH₂COO— (caprolactone moiety); andeach Y is independently selected from the group consisting of: —COCH₂O—(glycolic ester moiety); —COCH(CH₃)O— (lactic ester moiety); —COCH₂OCH₂CH₂O— (dioxanone ester moiety); and —COCH₂CH₂CH₂CH₂CH₂O— (caprolactoneester moiety).
 44. A polymer according to claim 42, wherein said monomercompound is an aminophenol, aminosalicylic acid or an aminobenzoic acid.45. An article comprising a metal or polymeric substrate for mammaliantissue contact and having thereon a coating, wherein said coatingcomprises at least one polymer according to claim
 42. 46. The article ofclaim 45, wherein said article is an implantable medical device.
 47. Animplantable medical device comprising at least one polymer according toclaim
 42. 48. A molded article characterized by being prepared from atleast one polymer according to claim
 42. 49. A controlled drug deliverysystem characterized by at least one polymer according to claim 42,physically admixed with a biologically or pharmacologically activeagent.
 50. A controlled drug delivery system characterized by abiologically or pharmacologically active agent physically embedded ordispersed into a polymeric matrix formed from at least one polymeraccording to claim
 42. 51. A tissue scaffold having a porous structurefor the attachment and proliferation of cells, either in vitro or invivo, characterized by being formed from one least one polymer accordingto claim
 42. 52. The polymer according to claim 42 wherein said polymeris polymerized on at least one end with at least one lactone monomerselected from the group consisting of glycolide, lactide, p-dioxanone,trimethylene carbonate and caprolactone.
 53. An implantable medicaldevice comprising at least one polymer according to claim
 52. 54. Amolded article characterized by being prepared from at least one polymeraccording to claim
 52. 55. A controlled drug delivery systemcharacterized by at least one polymer according to claim 52, physicallyadmixed with a biologically or pharmacologically active agent.
 56. Acontrolled drug delivery system characterized by a biologically orpharmacologically active agent physically embedded or dispersed into apolymeric matrix formed from at least one polymer according to claim 52.57. A tissue scaffold having a porous structure for the attachment andproliferation of cells, either in vitro or in vivo, characterized bybeing formed from at least one polymer according to claim
 52. 58. Atissue adhesive composition comprising at least one isocyanate compoundof the formula:

Wherein each X represents a member independently selected from the groupconsisting of: —CH₂COO— (glycolic acid moiety); —CH(CH₃)COO— (lacticacid moiety); —CH₂CH₂OCH₂COO— (dioxanone moiety); —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety); —(CH₂)_(y)COO— where y is one of the numbers2,3,4 and 6-24 inclusive; and —(CH₂CH₂O)_(z′)CH₂COO— where z′ is aninteger between 2 and 24, inclusive; each Y represents a memberindependently selected from the group consisting of: —COCH₂O— (glycolicester moiety); —COCH(CH₃)O— (lactic ester moiety); —COCH₂OCH₂CH₂O—(dioxanone ester moiety); —COCH₂CH₂CH₂CH₂CH₂O— (caprolactone estermoiety); —CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24inclusive; and —COCH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and24, inclusive; each R′ is hydrogen, benzyl or an alkyl group, the alkylgroup being either straight-chained or branched; each p is independentlyan integer between 1 and 4, inclusive; Z is O or NH; and Rn representsone or more members selected from the group consisting of H, alkoxy,benzyloxy, aldehyde, halogen, isocyanate, carboxylic acid and —NO₂,which is attached directly to an aromatic ring or attached through analiphatic chain.
 59. A composition according to claim 58 wherein each Xis independently selected from the group consisting of: —CH₂COO—(glycolic acid moiety), —CH(CH₃)COO— (lactic acid moiety),—CH₂CH₂OCH₂COO— (dioxanone moiety), and —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety); and each Y is independently selected from thegroup consisting of: —COCH₂O— (glycolic ester moiety); —COCH(CH₃)O—(lactic ester moiety); —COCH₂OCH₂CH₂O— (dioxanone ester moiety); and—COCH₂CH₂CH₂CH₂CH₂O— (caprolactone ester moiety).
 60. A compositionaccording to claim 58, wherein said isocyanate compound is anaminophenol, aminosalicylic acid or an aminobenzoic acid.
 61. Acomposition of claim 58 wherein said isocyanate compound contains morethan two isocyanate groups.
 62. A tissue adhesive composition comprisingat least one NCO— terminated hydrophilic urethane prepolymer preparedfrom at least one compound from claim 58 and a polyol component.
 63. Atissue adhesive composition according to claim 62, wherein said polyolcomponent is selected from the group consisting of polyether polyols.64. A method for closing a tissue defect comprising applying aneffective amount of the tissue adhesive composition of claim 58 oversaid tissue defect.
 65. A method for closing a tissue defect comprisingapplying an effective amount of the tissue adhesive composition of claim62 over said tissue defect.
 66. A compound selected from the groupconsisting of:

Wherein each X represents a member independently selected from the groupconsisting of: —CH₂COO— (glycolic acid moiety), —CH(CH₃)COO— (lacticacid moiety), —CH₂CH₂OCH₂COO— (dioxanone moiety), —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety), —(CH₂)_(y)COO— where y is one of the numbers2,3,4 or 6-24 inclusive, and —(CH₂CH₂O)_(z′)CH₂COO— where z′ is aninteger between 2 and 24, inclusive; each Y represents a memberindependently selected from the group consisting of: —COCH₂O— (glycolicester moiety), —COCH(CH₃)O— (lactic ester moiety), —COCH₂OCH₂CH₂O—(dioxanone ester moiety), —COCH₂CH₂CH₂CH₂CH₂O— (caprolactone estermoiety), —CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24inclusive, —COCH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and 24,inclusive; R′ is hydrogen, benzyl or an alkyl group, the alkyl groupbeing either straight-chained or branched; p is an integer between 1 and4, inclusive; and Rn represents one or more members selected from thegroup consisting of H, alkoxy, benzyloxy, aldehyde, halogen, carboxylicacid and —NO₂, which is attached directly to an aromatic ring orattached through an aliphatic chain.
 67. A compound selected from thegroup consisting of:

Wherein each X represents a member independently selected from the groupconsisting of: —CH₂COO— (glycolic acid moiety); —CH(CH₃)COO— (lacticacid moiety); —CH₂CH₂OCH₂COO— (dioxanone moiety); —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety); —(CH₂)_(y)COO— where y is one of the numbers2,3,4 and 6-24 inclusive; and —(CH₂CH₂O)_(z′)CH₂COO— where z′ is aninteger between 2 and 24, inclusive; each Y represents a memberindependently selected from the group consisting of: —COCH₂O— (glycolicester moiety); —COCH(CH₃)O— (lactic ester moiety); —COCH₂OCH₂CH₂O—(dioxanone ester moiety); —COCH₂CH₂CH₂CH₂CH₂O— (caprolactone estermoiety); —CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24inclusive; and —COCH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and24, inclusive; each R′ is independently a hydrogen, benzyl or an alkylgroup, the alkyl group being either straight-chained or branched; each pis independently an integer between 1 and 4, inclusive; Z is O or NH;and Rn represents one or more members selected from the group consistingof H, alkoxy, benzyloxy, aldehyde, halogen, carboxylic acid and —NO₂,which is attached directly to an aromatic ring or attached through analiphatic chain.
 68. A compound selected from the group consisting of:

Wherein each X represents a member independently selected from the groupconsisting of: —CH₂COO— (glycolic acid moiety); —CH(CH₃)COO— (lacticacid moiety); —CH₂CH₂OCH₂COO— (dioxanone moiety); —CH₂CH₂CH₂CH₂CH₂COO—(caprolactone moiety); —(CH₂)_(y)COO— where y is one of the numbers2,3,4 and 6-24 inclusive; and —(CH₂CH₂O)_(z′)CH₂COO— where z′ is aninteger between 2 and 24, inclusive; each Y represents a memberindependently selected from the group consisting of: —COCH₂O— (glycolicester moiety); —COCH(CH₃)O— (lactic ester moiety); —COCH₂OCH₂CH₂O—(dioxanone ester moiety); —COCH₂CH₂CH₂CH₂CH₂O— (caprolactone estermoiety); —CO(CH₂)_(m)O— where m is an integer between 2-4 and 6-24inclusive; and —COCH₂O(CH₂CH₂O)_(n)— where n is an integer between 2 and24, inclusive; each R′ is hydrogen, benzyl or an alkyl group, the alkylgroup being either straight-chained or branched; each p is independentlyan integer between 1 and 4, inclusive; Z is O or NH; and Rn representsone or more members selected from the group consisting of H, alkoxy,benzyloxy, aldehyde, halogen, carboxylic acid and —NO₂, which isattached directly to an aromatic ring or attached through an aliphaticchain.